How to center a subview of UIView

Question

I have a UIView inside a UIViewm and I want the inner UIView to be always centered inside the outer one  without it having to resize the width and height   I ve set the struts and springs so that it s on top left right bottom without setting the resize  But it still doesn t center  Any idea

User · Answer

I would use   child center   CGPointMake parent bounds height   2  parent bounds width   2    This is simple  short  and sweet  If you use  Hejazi s answer above and parent center is set to anything other than  0 0  your subview will not be centered

User · Answer

This worked for me childView centerXAnchor constraint equalTo  parentView centerXAnchor  isActive   true childView centerYAnchor constraint equalTo  parentView centerYAnchor  isActive   true

User · Answer

Set this autoresizing mask to your inner view

User · Answer

I would use   self childView center   CGPointMake CGRectGetMidX self parentView bounds                                       CGRectGetMidY self parentView bounds      I like to use the CGRect options     SWIFT 3   self childView center   CGPoint x  self parentView bounds midX                                          y  self parentView bounds midY

User · Answer

In c  or Xamarin ios  we can use like this  imageView Center   new CGPoint tempView Frame Size Width   2                                   tempView Frame Size Height   2

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With IOS9 you can use the layout anchor API   The code would look like this   childview centerXAnchor constraintEqualToAnchor parentView centerXAnchor  active   true childview centerYAnchor constraintEqualToAnchor parentView centerYAnchor  active   true   The advantage of this over CGPointMake or CGRect is that with those methods you are setting the center of the view to  a constant but with this technique you are setting a relationship between the two views that will hold forever  no matter how the parentview changes   Just be sure before you do this to do           self view addSubview parentView          self view addSubView chidview    and to set the translatesAutoresizingMaskIntoConstraints for each view to false   This will prevent crashing and AutoLayout from interfering

User · Answer

You can do this and it will always work   child center    parent convertPoint parent center fromView parent superview     And for Swift   child center   parent convert parent center  from parent superview

User · Answer

Before we ll begin  let s just remind that origin point is the Upper Left corner CGPoint of a view  An important thing to understand about views and parents   Lets take a look at this simple code  a view controller that adds to it s view a black square   class ViewController  UIViewController        override func viewDidLoad             super viewDidLoad              Do any additional setup after loading the view  typically from a nib          createDummyView           super view backgroundColor   UIColor cyanColor               func createDummyView            var subView   UIView frame  CGRect x  15  y  50  width  50   height  50            super view addSubview subView           view backgroundColor   UIColor blackColor              This will create this view  the black rectangle origin and center does fit the same coordinates as it s parent    Now let s try to add subView another SubSubView  and giving subSubview same origin as subView  but make subSubView a child view of subView  We ll add this code   var subSubView   UIView    subSubView frame origin   subView frame origin  subSubView frame size   CGSizeMake 20  20   subSubView backgroundColor   UIColor purpleColor   subView addSubview subSubView    And this is the result     Because of this line   subSubView frame origin   subView frame origin    You expect for the purple rectangle s origin to be same as it s parent  the black rectangle  but it goes under it  and why is that  Because when you add a view to another view  the subView frame  world  is now it s parent BOUND RECTANGLE  if you have a view that it s origin on the main screen is at coords  15 15  for all it s sub views  the upper left corner will be  0 0   This is why you need to always refer to a parent by it s bound rectangle  which is the  world  of it s subViews  lets fix this line to   subSubView frame origin   subView bounds origin    And see the magic  the subSubview is now located exactly in it s parent origin     So  you like  ok I only wanted to center my view by my parents view  what s the big deal    well  it isn t big deal  you just need to  translate  the parent Center point which is taken from it s frame to parent s bounds center by doing this   subSubView center   subView convertPoint subView center  fromView  subSubView     You re actually telling him  take parents view center  and convert it into subSubView world    And you ll get this result

User · Answer

Using the same center in the view and subview is the simplest way of doing it  You can do something like this   UIView  innerView         innerView view center   self view center   self view addSubView innerView

User · Answer

func callAlertView          UIView animate withDuration  0  animations            let H   self view frame height   0 4         let W   self view frame width   0 9         let X   self view bounds midX -  W 2          let Y   self view bounds midY -  H 2          self alertView frame   CGRect x X  y  Y  width  W  height  H          self alertView layer borderWidth   1         self alertView layer borderColor   UIColor red cgColor         self alertView layer cornerRadius   16         self alertView layer masksToBounds   true         self view addSubview self alertView                calculation works adjust H and W according to your requirement

User · Answer

The easiest way   child center   parent center

User · Answer

Another solution with PureLayout using autoCenterInSuperview          UIView  innerView    UIView newAutoLayoutView   innerView backgroundColor    UIColor greenColor    innerView autoSetDimensionsToSize CGSizeMake 100  30      outerview addSubview innerView     innerView autoCenterInSuperview     This is it how it looks like

User · Answer

Objective-C  yourSubView center   CGPointMake yourView frame size width    2                                    yourView frame size height   2     Swift  yourSubView center   CGPoint x  yourView frame size width    2                               y  yourView frame size height   2

User · Answer

You can use   yourView center   CGPointMake CGRectGetMidX superview bounds   CGRectGetMidY superview bounds     And In Swift 3 0   yourView center   CGPoint x  superview bounds midX  y  superview bounds midY

User · Answer

1  If you have autolayout enabled    Hint  For centering a view on another view with autolayout you can use same code for any two views sharing at least one parent view     First of all disable child views autoresizing  UIView  view1   view2   childview setTranslatesAutoresizingMaskIntoConstraints NO      If you are UIView Autolayout or Purelayout    view1 autoAlignAxis ALAxisHorizontal toSameAxisOfView view2    view1 autoAlignAxis ALAxisVertical toSameAxisOfView view2    If you are using only UIKit level autolayout methods    view1 addConstraints            NSLayoutConstraint        constraintWithItem view1        attribute NSLayoutAttributeCenterX        relatedBy NSLayoutRelationEqual        toItem view2        attribute NSLayoutAttributeCenterX        multiplier 1 f constant 0 f            NSLayoutConstraint         constraintWithItem view1         attribute NSLayoutAttributeCenterY         relatedBy NSLayoutRelationEqual         toItem view2         attribute NSLayoutAttributeCenterY         multiplier 1 f constant 0 f             2  Without autolayout   I prefer    UIView  parentView   childView   childView setFrame        CGRect frame   childView frame       frame origin x    parentView frame size width - frame size width    2 0      frame origin y    parentView frame size height - frame size height    2 0       CGRectIntegral frame

[iphone] How to center a subview of UIView

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