pragma mark in Swift

Question

In Objective C  I can use  pragma mark to mark sections of my code in the symbol navigator  Since this is a C preprocessor command  it s not available in Swift  Is there a stand-in for this in Swift  or do I have to use ugly comments

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In Objective-C code Xcode detects comments like    MARK  - foo which is a bit more portable than  pragma  But these do not seem to be picked up  too  yet     Edit  Fixed in Xcode 6 beta 4

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There are Three options to add  pragma mark in Swift   1     MARK  - your text here -  2     TODO  - your text here -  3     FIXME  - your text here -  Note  Uses  - for add separators

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Add a to-do item  Insert a comment with the prefix TODO    For   example     TODO   your to-do item        Add a bug fix reminder  Insert a comment with the prefix FIXME    For   example     FIXME   your bug fix reminder        Add a heading  Insert a comment with the prefix MARK    For example       MARK   your section heading        Add a separator line  To add a separator above an annotation  add a   hyphen  -  before the comment portion of the annotation   For example       MARK  -  your content   To add a separator below an annotation  add   a hyphen  -  after the comment portion of the annotation   For   example     MARK   your content  -

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You may also be interested in Swift 4 2   XCode 10 compiler directives like   warning  Some string to display     and    error  Some error to display     It might be useful when you really don t want to miss something

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Pragma mark -  SOME TEXT HERE  was used in Objective-C to group several function together by line separating   In Swift you can achieve this using MARK  TODO OR FIXME  i  MARK      MARK  viewDidLoad    This will create a horizontal line with functions grouped under viewDidLoad shown in screenshot 1     ii  TODO     TODO  - viewDidLoad  This will group function under TODO  - viewDidLoad category  shown in screenshot 2     iii  FIXME     FIXME - viewDidLoad   This will group function under FIXME  - viewDidLoad category  shown in screenshot 3     Check this apple documentation for details

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For those who are interested in using extensions vs pragma marks  as mentioned in the first comment   here is how to implement it from a Swift Engineer    import UIKit  class SwiftTableViewController  UITableViewController        init coder aDecoder  NSCoder             super init coder  aDecoder              override func viewDidLoad             super viewDidLoad             extension SwiftTableViewController       override func numberOfSectionsInTableView tableView  UITableView   - gt  Int           return 1            override func tableView tableView  UITableView   numberOfRowsInSection section  Int  - gt  Int           return 5            override func tableView tableView  UITableView   cellForRowAtIndexPath indexPath  NSIndexPath   - gt  UITableViewCell            let cell   tableView  dequeueReusableCellWithIdentifier  myCell   forIndexPath  indexPath  as UITableViewCell           cell textLabel text    Hello World           return cell            It s also not necessarily the best practice  but this is how you do it if you like

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Apple states in the latest version of Building Cocoa Apps       The Swift compiler does not include a preprocessor  Instead  it takes   advantage of compile-time attributes  build configurations  and   language features to accomplish the same functionality  For this   reason  preprocessor directives are not imported in Swift    The   character appears to still be how you work with various build configurations and things like that  but it looks like they re trying to cut back on your need for most preprocessing in the vein of pragma and forward you to other language features altogether   Perhaps this is to aid in the operation of the Playgrounds and the REPL behaving as close as possible to the fully compiled code

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Up to Xcode 5 the preprocessor directive  pragma mark existed   From Xcode 6 on  you have to use    MARK   These preprocessor features allow to bring some structure to the function drop down box of the source code editor   some examples       MARK    -  will be preceded by a horizontal divider     MARK  your text goes here   -  puts  your text goes here  in bold in the drop down list     MARK  - your text goes here   -  puts  your text goes here  in bold in the drop down list  preceded by a horizontal divider  update   added screenshot  cause some people still seem to have issues with this

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Use     MARK  SectionName   or     MARK  - SectionName   This will give a line above pragma mark  making it more readable   For ease just add      MARK  -  lt  label  gt    to your code snippets   Alternate way -  Use it in this way  private typealias SectionName   ViewController private extension SectionName           Your methods     This will not only add mark just like pragma mark  but also segregate the code nicely

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Pragma mark is a way to improve the readability of your code  The pragma comments would appear like tags on the Xcode jumpbar     MARK    lt Your comment goes here gt    Example  In the code     MARK  Properties     MARK  View Life cycle    MARK  Helper methods   This is how it would appear in the Xcode jump bar

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Xcode 8 now handles it as followed and shows up like this in the method dropdown

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Official Documentation  Apple s official document about Xcode Jump Bar  Add code annotations to the jump bar  Jump Bar Screenshots for Sample Code        Behavior in Xcode 10 1 and macOS 10 14 3  Mojave         Behavior in Xcode 10 0 and macOS 10 13 4  High Sierra         Behavior in Xcode 9 4 1 and macOS 10 13 0        Discussion       and      sometimes are not able to be displayed

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In Xcode 11 they added minimap which can be activated Editor - gt  Minimap   Minimap will show each mark text for fast orientation in code  Each mark is written like    MARK  Variables

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MARK  - Spinner Class Methods   Add a line between the colon and your description to insert a separator line  This helps to organize your code even more  The code and screenshot above make use of the MARK comment with a line included        MARK      Text Methods  LINE       MARK  Text Methods  NO LINE    This only works with the MARK comment

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MARK  does not seem to work for me in Xcode 6 3 2   However  this is what I did to get it to work   1  Code   import Cocoa  class MainWindowController  NSWindowController          MARK  - My cool methods      func fly                func turnInvisible                2  In the jump bar nothing appears to change when adding the   MARK  comment   However  if I click on the rightmost name in the jump bar  in my case it says MainWindowController with a leading C icon   then a popup window will display showing the effects of the   MARK  comment  namely a heading that says  My cool methods      3  I also notice that if I click on one of the methods in my code  then the method becomes the rightmost entry in the jump bar   In order to get MainWindowController with a leading C icon  to be the rightmost entry in the jump bar  I have to click on the whitespace above my methods

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You can use    MARK     There has also been discussion that liberal use of class extensions might be a better practice anyway  Since extensions can implement protocols  you can e g  put all of your table view delegate methods in an extension and group your code at a more semantic level than  pragma mark is capable of

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I think Extensions is a better way instead of  pragma mark   The Code before using Extensions   class ViewController  UIViewController  UICollectionViewDataSource  UICollectionViewDelegate                func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int                          func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell                          func collectionView   collectionView  UICollectionView  didSelectItemAt indexPath  IndexPath                          The code after using Extensions   class ViewController  UIViewController              extension ViewController  UICollectionViewDataSource       func collectionView   collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int                          func collectionView   collectionView  UICollectionView  cellForItemAt indexPath  IndexPath  - gt  UICollectionViewCell                        extension ViewController  UICollectionViewDelegate       func collectionView   collectionView  UICollectionView  didSelectItemAt indexPath  IndexPath

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Try this      MARK  Reload TableView  func reloadTableView         tableView reload

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Professional programer must be use this tag for good code   It is also good for team work        MARK  example Web Service start here    TODO  example 1    FIXME  Please change BASE url before live    It is easy to find method like this

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Confirmed with an Apple Engineer in the Swift lab this morning at WWDC that there currently aren t any  pragma or equivalent at the moment  they consider this a bug  and it will arrive soon  so I am guessing beta 2  I hope   Anyway  it s on it s way      Xcode now supports   MARK     TODO  and   FIXME landmarks to annotate your code and  lists them in the jump bar

[swift] #pragma mark in Swift?

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