Zooming MKMapView to fit annotation pins

Question

I am using MKMapView and have added a number of annotation pins to the map about a 5-10 kilometre area  When I run the application my map starts zoomed out to show the whole world  what is the best way to zoom the map so the pins fit the view   EDIT  My initial thinking would be to use MKCoordinateRegionMake and calculate the coordinate centre  longitudeDelta and latitudeDelta from my annotations  I am pretty sure this will work  but I just wanted to check I was not missing anything obvious   Code added  BTW  FGLocation is an class that conforms to MKAnnotation  locationFake is an NSMutableArray of these objects  Comments are always welcome       -  MKCoordinateRegion regionFromLocations       CLLocationCoordinate2D upper     locationFake objectAtIndex 0  coordinate       CLLocationCoordinate2D lower     locationFake objectAtIndex 0  coordinate           FIND LIMITS     for FGLocation  eachLocation in locationFake            if  eachLocation coordinate  latitude  gt  upper latitude  upper latitude    eachLocation coordinate  latitude          if  eachLocation coordinate  latitude  lt  lower latitude  lower latitude    eachLocation coordinate  latitude          if  eachLocation coordinate  longitude  gt  upper longitude  upper longitude    eachLocation coordinate  longitude          if  eachLocation coordinate  longitude  lt  lower longitude  lower longitude    eachLocation coordinate  longitude                FIND REGION     MKCoordinateSpan locationSpan      locationSpan latitudeDelta   upper latitude - lower latitude      locationSpan longitudeDelta   upper longitude - lower longitude      CLLocationCoordinate2D locationCenter      locationCenter latitude    upper latitude   lower latitude    2      locationCenter longitude    upper longitude   lower longitude    2       MKCoordinateRegion region   MKCoordinateRegionMake locationCenter  locationSpan       return region

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var zoomRect  MKMapRect   MKMapRect null     for annotation in mapView annotations           let annotationPoint   MKMapPoint annotation coordinate          let pointRect   MKMapRect x  annotationPoint x  y  annotationPoint y  width  0 1  height  0 1          zoomRect   zoomRect union pointRect            mapView setVisibleMapRect zoomRect  animated  true       Edited for swift 5

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I have converted the answer by Rafael Moreira  The credit goes to him  For those of you looking for the Swift version  here is the code    func zoomToFitMapAnnotations aMapView  MKMapView        guard aMapView annotations count  gt  0 else           return           var topLeftCoord  CLLocationCoordinate2D   CLLocationCoordinate2D       topLeftCoord latitude   -90     topLeftCoord longitude   180     var bottomRightCoord  CLLocationCoordinate2D   CLLocationCoordinate2D       bottomRightCoord latitude   90     bottomRightCoord longitude   -180     for annotation  MKAnnotation in myMap annotations as   MKAnnotation           topLeftCoord longitude   fmin topLeftCoord longitude  annotation coordinate longitude          topLeftCoord latitude   fmax topLeftCoord latitude  annotation coordinate latitude          bottomRightCoord longitude   fmax bottomRightCoord longitude  annotation coordinate longitude          bottomRightCoord latitude   fmin bottomRightCoord latitude  annotation coordinate latitude             var region  MKCoordinateRegion   MKCoordinateRegion       region center latitude   topLeftCoord latitude -  topLeftCoord latitude - bottomRightCoord latitude    0 5     region center longitude   topLeftCoord longitude    bottomRightCoord longitude - topLeftCoord longitude    0 5     region span latitudeDelta   fabs topLeftCoord latitude - bottomRightCoord latitude    1 4     region span longitudeDelta   fabs bottomRightCoord longitude - topLeftCoord longitude    1 4     region   aMapView regionThatFits region      myMap setRegion region  animated  true

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All the answers on this page assume that the map occupies the full screen  I actually have a HUD display  ie buttons scattered at the top and bottom  that give information ontop of the map   and so the algorithms on the page will display the pins all right  but some of them will appear under the HUD display buttons   My solution zooms the map in to display the annotations in a subset of the screen and works for different screen sizes  ie 3 5  vs 4 0  etc       create a UIView placeholder and throw it on top of the original mapview    position the UIView to fit the maximum area not hidden by the HUD display buttons    add an  other  mapview in that uiview      get the MKCoordinateRegion that fits the pins from that fake mapview    kill the fake mapview and set the region of the original map     to that MKCoordinateRegion    Here is what I did in code  note  i use NSConstraints with some helper methods to make my code work in different screen sizes   while the code is quite readable   my answer here explains it better   it s basically the same workflow       position smallerMap to fit available space    don t store this map  it will slow down things if we keep it hidden or even in memory     smallerMapPlaceholder  mapObjectsApplyingBlock   UIView  view         view removeFromSuperview        view setTranslatesAutoresizingMaskIntoConstraints NO        view setHidden NO        self view addSubview view        NSDictionary  buttonBindingDict        mapPlaceholder    smallerMapPlaceholder    NSArray  constraints        V  -225- mapPlaceholder  gt  50  -176-                                 -40- mapPlaceholder  lt  240  -40-                               mapObjectsUsingBlock  id NSString  formatString  NSUInteger idx                                 return  NSLayoutConstraint constraintsWithVisualFormat formatString options 0 metrics nil views buttonBindingDict                                   self view addConstraints  constraints flattenArray     self view layoutIfNeeded    MKMapView  smallerMap     MKMapView alloc  initWithFrame self smallerMapPlaceholder frame     smallerMapPlaceholder addSubview smallerMap    MKCoordinateRegion regionThatFits    smallerMap getRegionThatFits self mapView annotations    smallerMap removeFromSuperview   smallerMap   nil    smallerMapPlaceholder setHidden YES     self mapView setRegion regionThatFits animated YES     here is the code that gets region that fits   -  MKCoordinateRegion getRegionThatFits  NSArray   routes       MKCoordinateRegion region      CLLocationDegrees maxLat   -90 0      CLLocationDegrees maxLon   -180 0      CLLocationDegrees minLat   90 0      CLLocationDegrees minLon   180 0      for int idx   0  idx  lt  routes count  idx                  CLLocation  currentLocation    routes objectAtIndex idx           if currentLocation coordinate latitude  gt  maxLat              maxLat   currentLocation coordinate latitude          if currentLocation coordinate latitude  lt  minLat              minLat   currentLocation coordinate latitude          if currentLocation coordinate longitude  gt  maxLon              maxLon   currentLocation coordinate longitude          if currentLocation coordinate longitude  lt  minLon              minLon   currentLocation coordinate longitude            region center latitude        maxLat   minLat    2 0      region center longitude       maxLon   minLon    2 0      region span latitudeDelta   0 01      region span longitudeDelta   0 01       region span latitudeDelta      maxLat - minLat  lt 0 0  100 0  maxLat - minLat       region span longitudeDelta     maxLon - minLon  lt 0 0  100 0  maxLon - minLon        MKCoordinateRegion regionThatFits    self regionThatFits region       return regionThatFits

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jowie s solution works great  One catch  if a map has only one annotation you ll end up with a fully zoomed out map  I added 0 1 to the rect make size to make sure setVisibleMapRect has something to zoom to   MKMapRect pointRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1

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I created an extension to show all the annotations using some code from here and there in swift  This will not show all annotations if they can t be shown even at maximum zoom level   import MapKit  extension MKMapView       func fitAllAnnotations             var zoomRect   MKMapRectNull          for annotation in annotations               let annotationPoint   MKMapPointForCoordinate annotation coordinate              let pointRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1               zoomRect   MKMapRectUnion zoomRect  pointRect                     setVisibleMapRect zoomRect  edgePadding  UIEdgeInsets top  50  left  50  bottom  50  right  50   animated  true

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You ve got it right   Find your maximum and minimum latitudes and longitudes  apply some simple arithmetic  and use MKCoordinateRegionMake   For iOS 7 and above  use showAnnotations animated   from MKMapView h      Position the map such that the provided array of annotations are all visible to the fullest extent possible   -  void showAnnotations  NSArray   annotations animated  BOOL animated NS AVAILABLE 10 9  7 0

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This is the one I found here that worked for me    EDIT  I have updated the solution using  Micah s suggestion to increase the pointRect by 0 1 to ensure the rect doesn t end up being infinitesimally small    MKMapRect zoomRect   MKMapRectNull  for  id  lt MKAnnotation gt  annotation in mapView annotations        MKMapPoint annotationPoint   MKMapPointForCoordinate annotation coordinate       MKMapRect pointRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1       zoomRect   MKMapRectUnion zoomRect  pointRect      mapView setVisibleMapRect zoomRect animated YES      nbsp   You could also update this to include the userLocation pin by replacing the first line with   MKMapPoint annotationPoint   MKMapPointForCoordinate mapView userLocation coordinate   MKMapRect zoomRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1

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Thanks to jowie I ve updated my old category to more elegant solution  Sharing complete  almost copy amp paste ready solution  MKMapView AnnotationsRegion h   import  lt MapKit MapKit h gt    interface MKMapView  AnnotationsRegion   - void updateRegionForCurrentAnnotationsAnimated  BOOL animated  - void updateRegionForCurrentAnnotationsAnimated  BOOL animated edgePadding  UIEdgeInsets edgePadding   - void updateRegionForAnnotations  NSArray   annotations animated  BOOL animated  - void updateRegionForAnnotations  NSArray   annotations animated  BOOL animated edgePadding  UIEdgeInsets edgePadding    end   MKMapView AnnotationsRegion m   import  MKMapView AnnotationsRegion h    implementation MKMapView  AnnotationsRegion   - void updateRegionForCurrentAnnotationsAnimated  BOOL animated       self updateRegionForCurrentAnnotationsAnimated animated edgePadding UIEdgeInsetsZero     - void updateRegionForCurrentAnnotationsAnimated  BOOL animated edgePadding  UIEdgeInsets edgePadding       self updateRegionForAnnotations self annotations animated animated edgePadding edgePadding      - void updateRegionForAnnotations  NSArray   annotations animated  BOOL animated       self updateRegionForAnnotations annotations animated animated edgePadding UIEdgeInsetsZero     - void updateRegionForAnnotations  NSArray   annotations animated  BOOL animated edgePadding  UIEdgeInsets edgePadding      MKMapRect zoomRect   MKMapRectNull      for id lt MKAnnotation gt  annotation in annotations           MKMapPoint annotationPoint   MKMapPointForCoordinate annotation coordinate           MKMapRect pointRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1           zoomRect   MKMapRectUnion zoomRect  pointRect              self setVisibleMapRect zoomRect edgePadding edgePadding animated animated       end   Hope it helps someone and thanks again jowie

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Based on answers above you can use universal method to zoom map to fit all annotations and overlays at the same time   - MKMapRect getZoomingRectOnMap  MKMapView  map toFitAllOverlays  BOOL overlays andAnnotations  BOOL annotations includeUserLocation  BOOL userLocation       if   map            return MKMapRectNull             NSMutableArray  overlaysAndAnnotationsCoordinateArray     NSMutableArray alloc init               if  overlays            for  id  lt MKOverlay gt  overlay in map overlays                MKMapPoint overlayPoint   MKMapPointForCoordinate overlay coordinate               NSArray  coordinate      NSNumber numberWithDouble overlayPoint x    NSNumber numberWithDouble overlayPoint y                 overlaysAndAnnotationsCoordinateArray addObject coordinate                        if  annotations            for  id  lt MKAnnotation gt  annotation in map annotations                MKMapPoint annotationPoint   MKMapPointForCoordinate annotation coordinate               NSArray  coordinate      NSNumber numberWithDouble annotationPoint x    NSNumber numberWithDouble annotationPoint y                 overlaysAndAnnotationsCoordinateArray addObject coordinate                        MKMapRect zoomRect   MKMapRectNull      if  userLocation            MKMapPoint annotationPoint   MKMapPointForCoordinate map userLocation coordinate           zoomRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1              for  NSArray  coordinate in overlaysAndAnnotationsCoordinateArray            MKMapRect pointRect   MKMapRectMake  coordinate 0  doubleValue    coordinate 1  doubleValue   0 1  0 1           zoomRect   MKMapRectUnion zoomRect  pointRect              return zoomRect      And then   MKMapRect mapRect    self getZoomingRectOnMap mapView toFitAllOverlays YES andAnnotations YES includeUserLocation NO    mapView setVisibleMapRect mapRect edgePadding UIEdgeInsetsMake 10 0  10 0  10 0  10 0  animated YES

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In Swift       var zoomRect   MKMapRectNull       for i in 0   lt self map annotations count            let annotation  MKAnnotation   self map annotations i           let annotationPoint   MKMapPointForCoordinate annotation coordinate           let pointRect   MKMapRectMake annotationPoint x  annotationPoint y  0 1  0 1           zoomRect   MKMapRectUnion zoomRect  pointRect              self map setVisibleMapRect zoomRect  animated  true

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In Swift use   mapView showAnnotations annotationArray  animated  true    In Objective c   mapView showAnnotations annotationArray animated YES

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Put this in to your code accordingly      -  void mapView  MKMapView   mv didAddAnnotationViews  NSArray   views           id lt MKAnnotation gt  mp    annotationView annotation           MKCoordinateRegion region   MKCoordinateRegionMakeWithDistance  mp coordinate   250 250            mv setRegion region animated YES

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I use this this code and works fine for me   - void zoomToFitMapAnnotations  MKMapView  aMapView       if  aMapView annotations count     0          return       CLLocationCoordinate2D topLeftCoord      topLeftCoord latitude   -90      topLeftCoord longitude   180       CLLocationCoordinate2D bottomRightCoord      bottomRightCoord latitude   90      bottomRightCoord longitude   -180       for MapViewAnnotation  annotation in mapView annotations                topLeftCoord longitude   fmin topLeftCoord longitude  annotation coordinate longitude           topLeftCoord latitude   fmax topLeftCoord latitude  annotation coordinate latitude            bottomRightCoord longitude   fmax bottomRightCoord longitude  annotation coordinate longitude           bottomRightCoord latitude   fmin bottomRightCoord latitude  annotation coordinate latitude              MKCoordinateRegion region      region center latitude   topLeftCoord latitude -  topLeftCoord latitude - bottomRightCoord latitude    0 5      region center longitude   topLeftCoord longitude    bottomRightCoord longitude - topLeftCoord longitude    0 5      region span latitudeDelta   fabs topLeftCoord latitude - bottomRightCoord latitude    1 1     Add a little extra space on the sides     region span longitudeDelta   fabs bottomRightCoord longitude - topLeftCoord longitude    1 1     Add a little extra space on the sides      region    aMapView regionThatFits region        mapView setRegion region animated YES

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I m not sure if this is because of some other factors in my implementation  but I find that showAnnotations doesn t do as close a zoom fit of the annotations as the manual implementation does  so I ve stuck with the manual one       Ted Avery Apr 17 at 0 35   I had the same problem  but then I tried doing showAnnotations twice  like below   and for some reason  it worked    mapView showAnnotations yourAnnotationArray animated YES    mapView showAnnotations yourAnnotationArray animated YES

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Just sharing my observations on this    If you are using xCode   6 with  inferred  sizes for the screens  see  simulated metrics  on the file inspector  in storyboard  calling   -  void showAnnotations  NSArray   annotations                animated  BOOL animated  in viewDidLoad will result in a too large zoom level on iPhones with 4 inches because the layout for the map is still on the size of the wider screens from the storyboard    You can move your call to showAnnotations    to viewDidAppear  Then the size of the map has already been adjusted to the smaller screen of an iPhone 4    Or alternatively change the value  inferred  in the file inspector under  simulated metrics  to iphone 4-inch

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As Abhishek Bedi points out in a comment  For iOS7 forward the best way to do this is     from API docs     -  void showAnnotations  NSArray   annotations animated  BOOL animated NS AVAILABLE 10 9  7 0    self mapView showAnnotations self mapView annotations animated YES     For my personal project  prior to iOS7  I simply added a category on the MKMapView class to encapsulate the  visible area  functionality for a very common operation  setting it to be able to see all the currently-loaded annotations on the MKMapView instance  this includes as many pins as you might have placed  as well as the user s location   the result was this    h file   import  lt MapKit MapKit h gt    interface MKMapView  Extensions   - void ij setVisibleRectToFitAllLoadedAnnotationsAnimated  BOOL animated  - void ij setVisibleRectToFitAnnotations  NSArray   annotations animated  BOOL animated     end    m file   import  MKMapView Extensions h    implementation MKMapView  Extensions           Changes the currently visible portion of the map to a region that best fits all the currently loadded annotations on the map  and it optionally animates the change          param animated is the change should be perfomed with an animation      - void ij setVisibleRectToFitAllLoadedAnnotationsAnimated  BOOL animated       MKMapView   mapView   self       NSArray   annotations   mapView annotations        self ij setVisibleRectToFitAnnotations annotations animated animated                Changes the currently visible portion of the map to a region that best fits the provided annotations array  and it optionally animates the change      All elements from the array must conform to the  lt MKAnnotation gt  protocol in order to fetch the coordinates to compute the visible region of the map          param annotations an array of elements conforming to the  lt MKAnnotation gt  protocol  holding the locations for which the visible portion of the map will be set       param animated    wether or not the change should be perfomed with an animation      - void ij setVisibleRectToFitAnnotations  NSArray   annotations animated  BOOL animated       MKMapView   mapView   self       MKMapRect r   MKMapRectNull      for  id lt MKAnnotation gt  a in annotations            ZAssert  a conformsToProtocol  protocol MKAnnotation      ERROR  All elements of the array MUST conform to the MKAnnotation protocol  Element      did not fulfill this requirement   a           MKMapPoint p   MKMapPointForCoordinate a coordinate             MKMapRectUnion performs the union between 2 rects  returning a bigger rect containing both  or just one if the other is null   here we do it for rects without a size  points          r   MKMapRectUnion r  MKMapRectMake p x  p y  0  0                mapView setVisibleMapRect r animated animated        end   As you can see  I ve added 2 methods so far  one for setting the visible region of the map to the one that fits all currently-loaded annotations on the MKMapView instance  and another method to set it to any array of  objects  So to set the mapView s visible region the code would then be as simple as        the mapView instance        self mapView ij setVisibleRectToFitAllLoadedAnnotationsAnimated animated      I hope it helps

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Swift 3 This is de correct way for fit all annotations in map   func zoomMapaFitAnnotations              var zoomRect   MKMapRectNull         for annotation in mapview annotations                let annotationPoint   MKMapPointForCoordinate annotation coordinate               let pointRect   MKMapRectMake annotationPoint x  annotationPoint y  0  0               if  MKMapRectIsNull zoomRect                     zoomRect   pointRect               else                   zoomRect   MKMapRectUnion zoomRect  pointRect                                  self mapview setVisibleMapRect zoomRect  edgePadding  UIEdgeInsetsMake 50  50  50  50   animated  true

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Apple has added a new method for IOS 7 to simplify life a bit    mapView showAnnotations yourAnnotationArray animated YES     You can easily pull from an array stored in the map view   yourAnnotationArray   mapView annotations    and quickly adjust the camera too   mapView camera altitude    1 4    this won t work unless the user has iOS 7  or OS X 10 9  installed  check out custom animation here

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If your are looking for iOS 8 and above  the simplest way to do it is to set the var layoutMargins  UIEdgeInsets   get set   of your map view before calling func showAnnotations annotations   MKAnnotation   animated  Bool    For instance  Swift 2 1     IBOutlet weak var map  MKMapView        didSet           map delegate   self         map mapType    Standard         map pitchEnabled   false         map rotateEnabled   false         map scrollEnabled   true         map zoomEnabled   true             call  updateView    when viewWillAppear or whenever you set the map annotations func updateView         map layoutMargins   UIEdgeInsets top  25  left  25  bottom  25  right  25      map showAnnotations map annotations  animated  true

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You can select which shapes you want to show along with the Annotations   extension MKMapView     func setVisibleMapRectToFitAllAnnotations animated  Bool   true                                              shouldIncludeUserAccuracyRange  Bool   true                                              shouldIncludeOverlays  Bool   true                                              edgePadding  UIEdgeInsets   UIEdgeInsets top  35  left  35  bottom  35  right  35         var mapOverlays   overlays      if shouldIncludeUserAccuracyRange  let userLocation   userLocation location         let userAccuracyRangeCircle   MKCircle center  userLocation coordinate  radius  userLocation horizontalAccuracy        mapOverlays append MKOverlayRenderer overlay  userAccuracyRangeCircle  overlay             if shouldIncludeOverlays         let annotations   self annotations filter      0 is MKUserLocation          annotations forEach   annotation in         let cirlce   MKCircle center  annotation coordinate  radius  1          mapOverlays append cirlce                     let zoomRect   MKMapRect bounding  mapOverlays      setVisibleMapRect zoomRect  edgePadding  edgePadding  animated  animated         extension MKMapRect     init bounding overlays   MKOverlay         self    null     overlays forEach   overlay in       let rect  MKMapRect   overlay boundingMapRect       self   self union rect

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For iOS 7 and above  Referring MKMapView h          Position the map such that the provided array of annotations are all visible to the fullest extent possible             -  void showAnnotations  NSArray   annotations animated  BOOL animated NS AVAILABLE 10 9  7 0     remark from      Abhishek Bedi  You just call     yourMapView showAnnotations   yourAnnotation  animated YES

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-  void zoomMapViewToFitAnnotationsWithExtraZoomToAdjust  double extraZoom        if   self annotations count     0  return      int i   0    MKMapPoint points  self annotations count        for  id lt MKAnnotation gt  annotation in  self annotations             points i      MKMapPointForCoordinate annotation coordinate           MKPolygon  poly    MKPolygon polygonWithPoints points count i    MKCoordinateRegion r   MKCoordinateRegionForMapRect  poly boundingMapRect    r span latitudeDelta    extraZoom  r span longitudeDelta    extraZoom    self setRegion  r animated YES

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I ve made a little modification of Rafael s code for MKMapView Category   -  void zoomToFitMapAnnotations       if   self annotations count     0          return       CLLocationCoordinate2D topLeftCoord      topLeftCoord latitude   -90      topLeftCoord longitude   180       CLLocationCoordinate2D bottomRightCoord      bottomRightCoord latitude   90      bottomRightCoord longitude   -180       for  id  lt MKAnnotation gt  annotation in self annotations            topLeftCoord longitude   fmin topLeftCoord longitude  annotation coordinate longitude           topLeftCoord latitude   fmax topLeftCoord latitude  annotation coordinate latitude            bottomRightCoord longitude   fmax bottomRightCoord longitude  annotation coordinate longitude           bottomRightCoord latitude   fmin bottomRightCoord latitude  annotation coordinate latitude              MKCoordinateRegion region      region center latitude   topLeftCoord latitude -  topLeftCoord latitude - bottomRightCoord latitude    0 5      region center longitude   topLeftCoord longitude    bottomRightCoord longitude - topLeftCoord longitude    0 5      region span latitudeDelta   fabs topLeftCoord latitude - bottomRightCoord latitude    1 1     Add a little extra space on the sides     region span longitudeDelta   fabs bottomRightCoord longitude - topLeftCoord longitude    1 1     Add a little extra space on the sides       self setRegion  self regionThatFits region  animated YES

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An iOS 7 compatible way is to use the following  First call showAnnotation in order to get a rectangle including all annotations  Afterwards create and UIEdgeInset with an top inset of the pin height  Thus you ensure to show the whole pin on the map    self mapView showAnnotations self mapView annotations animated YES   MKMapRect rect    self mapView visibleMapRect   UIEdgeInsets insets   UIEdgeInsetsMake pinHeight  0  0  0    self mapView setVisibleMapRect rect edgePadding insets animated YES

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Added this If loop within the for loop to exclude the users location pin from this method  required in my case  and maybe others   if    annotation isKindOfClass  MKUserLocation class          Code Here

[ios] Zooming MKMapView to fit annotation pins?

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