Passing parameters to addTarget action forControlEvents

Question

I am using addTarget action forControlEvents like this    newsButton addTarget self action  selector switchToNewsDetails  forControlEvents UIControlEventTouchUpInside     and I would like to pass parameters to my selector  switchToNewsDetails   The only thing I succeed in doing is to pass the  id sender by writing  action  selector switchToNewsDetails    But I am trying to pass variables like integer values  Writing it this way doesn t work    int i   0   newsButton addTarget self action  selector switchToNewsDetails i  forControlEvents UIControlEventTouchUpInside     Writing it this way does not work either   int i   0   newsButton addTarget self action  selector switchToNewsDetails i   forControlEvents UIControlEventTouchUpInside     Any help would be appreciated

User · Answer

I subclassed UIButton in CustomButton and I add a property where I store my data. So I call method: (CustomButton*) sender and in the method I only read my data sender.myproperty.

Example CustomButton:

@interface CustomButton : UIButton
@property(nonatomic, retain) NSString *textShare;
@end

Method action:

+ (void) share: (CustomButton*) sender
{
    NSString *text = sender.textShare;
    //your work…
}

Assign action

    CustomButton *btn = [[CustomButton alloc] initWithFrame: CGRectMake(margin, margin, 60, 60)];
    // other setup…

    btnWa.textShare = @"my text";
    [btn addTarget: self action: @selector(shareWhatsapp:)  forControlEvents: UIControlEventTouchUpInside];

User · Answer

As there are many ways mentioned here for the solution  Except category feature       Use the category feature to extend defined built-in  element into your   customisable element    For instance ex      interface UIButton  myData    property  strong  nonatomic  id btnData    end   in the your view Controller m    import  UIButton myAppLists h   UIButton  myButton      btn intialisation       myButton set btnData   my own Data     myButton addTarget self action  selector buttonClicked   forControlEvents UIControlEventTouchUpInside     Event handler   - void buttonClicked    UIButton  sender      NSLog   my Data      sender  btnData

User · Answer

action  selector switchToNewsDetails     You do not pass parameters to switchToNewsDetails  method here  You just create a selector to make button able to call it when certain action occurs  touch up in your case   Controls can use 3 types of selectors to respond to actions  all of them have predefined meaning of their parameters    with no parameters  action  selector switchToNewsDetails   with 1 parameter indicating the control that sends the message  action  selector switchToNewsDetails    With 2 parameters indicating  the control that sends the message and the event that triggered the message    action  selector switchToNewsDetails event      It is not clear what exactly you try to do  but considering you want to assign a specific details index to each button you can do the following    set a tag property to each button equal to required index in switchToNewsDetails  method you can obtain that index and open appropriate deatails   -  void switchToNewsDetails  UIButton  sender       self openDetails sender tag          Or place opening logic right here

User · Answer

This fixed my problem but it crashed unless I changed   action  selector switchToNewsDetails event                      to  action  selector switchToNewsDetails  forEvent

User · Answer

There is another one way  in which you can get indexPath of the cell where your button was pressed   using usual action selector like    UIButton  btn              btn addTarget self action  selector yourFunction   forControlEvents UIControlEventTouchUpInside     and then in in yourFunction      -  void  yourFunction  id sender        UIButton  button   sender      CGPoint center   button center      CGPoint rootViewPoint    button superview convertPoint center toView self tableView       NSIndexPath  indexPath    self tableView indexPathForRowAtPoint rootViewPoint         the rest of your code goes here            since you get an indexPath it  becames much simplier

User · Answer

If you just want to change the text for the leftBarButtonItem shown by the navigation controller together with the new view  you may change the title of the current view just before calling pushViewController to the wanted text and restore it in the viewHasDisappered callback for future showings of the current view   This approach keeps the functionality  popViewController  and the appearance of the shown arrow intact   It works for us at least with iOS 12  built with Xcode 10 1

User · Answer

I was creating several buttons for each phone number in an array so each button needed a different phone number to call  I used the setTag function as I was creating several buttons within a for loop   for  NSInteger i   0  i  lt   phoneNumbers count  i           UIButton  phoneButton     UIButton alloc  initWithFrame someFrame        phoneButton setTitle  phoneNumbers i  forState UIControlStateNormal         phoneButton setTag i         phoneButton addTarget self                     action  selector call             forControlEvents UIControlEventTouchUpInside       Then in my call  method I used the same for loop and an if statement to pick the correct phone number   -  void call  UIButton   sender       for  NSInteger i   0  i  lt   phoneNumbers count  i              if  sender tag    i                NSString  callString    NSString stringWithFormat   telprompt         phoneNumbers i                  UIApplication sharedApplication  openURL  NSURL URLWithString callString

User · Answer

See my comment above  and I believe you have to use NSInvocation when there is more than one parameter  more information on NSInvocation here  http   cocoawithlove com 2008 03 construct-nsinvocation-for-any-message html

User · Answer

Target-Action allows three different forms of action selector   -  void action -  void action  id sender -  void action  id sender forEvent  UIEvent   event

User · Answer

Need more than just an  int  via  tag  Use KVC  You can pass any data you want through the button object itself  by accessing CALayers keyValue dict    Set your target like this  with the  quot   quot    myButton addTarget self action  selector buttonTap   forControlEvents UIControlEventTouchUpInside     Add your data s  to the button itself  well the  layer of the button that is  like this  NSString  dataIWantToPass     quot this is my data quot    can be anything  doesn t have to be NSString  myButton layer setValue dataIWantToPass forKey   quot anyKey quot     you can set as many of these as you d like too    Then when the button is tapped you can check it like this  - void buttonTap  UIButton  sender       NSString  dataThatWasPassed    NSString    sender layer valueForKey   quot anyKey quot        NSLog   quot My passed-thru data was     quot   dataThatWasPassed

User · Answer

To pass custom params along with the button click you just need to SUBCLASS UIButton    ASR is on  so there s no releases in the code    This is myButton h   import  lt UIKit UIKit h gt    interface myButton   UIButton       id userData      property  nonatomic  readwrite  retain  id userData    end   This is myButton m   import  myButton h   implementation myButton  synthesize userData   end   Usage   myButton  bt    myButton buttonWithType UIButtonTypeCustom    bt setFrame CGRectMake 0 0  100  100     bt setExclusiveTouch NO    bt setUserData    insert user data here        bt addTarget self action  selector touchUpHandler   forControlEvents UIControlEventTouchUpInside     view addSubview bt     Recieving function   -  void  touchUpHandler  myButton   sender       id userData   sender userData      If you need me to be more specific on any part of the above code     feel free to ask about it in comments

User · Answer

You can replace target-action with a closure  block in Objective-C  by adding a helper closure wrapper  ClosureSleeve  and adding it as an associated object to the control so it gets retained  That way you can pass any parameters   Swift 3  class ClosureSleeve       let closure     - gt          init attachTo  AnyObject  closure   escaping    - gt                self closure   closure         objc setAssociatedObject attachTo      arc4random       self   OBJC ASSOCIATION RETAIN              objc func invoke             closure            extension UIControl       func addAction for controlEvents  UIControlEvents  action   escaping    - gt                let sleeve   ClosureSleeve attachTo  self  closure  action          addTarget sleeve  action   selector ClosureSleeve invoke   for  controlEvents            Usage   button addAction for   touchUpInside        self switchToNewsDetails parameter  i

User · Answer

I made a solution based in part by the information above  I just set the titlelabel text to the string I want to pass  and set the titlelabel hidden   YES  Like this    UIButton  imageclick     UIButton buttonWithType UIButtonTypeCustom  retain   imageclick frame   photoframe  imageclick titleLabel text    NSString stringWithFormat           ti mediaImage  ti mediaExtension   imageclick titleLabel hidden   YES    This way  there is no need for a inheritance or category and there is no memory leak

[ios] Passing parameters to addTarget:action:forControlEvents

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