UIButton子类不响应超级方法？

Question

I would like to create a UIButton that toggles its image. Once clicked the image should change to another one and stay that way until clicked again.

I have added both images to the default and selected states of the button on interface builder.

Now, I have created a UIButton subclass. My idea is to intercept the tap to that button and change the button state. So I added this to the UIButton subclass, hoping one of these methods would be triggered by a tap.

- (void)sendAction:(SEL)action
                to:(id)target
          forEvent:(UIEvent *)event {

  [super sendAction:action to:target forEvent:event];

  // toggle state
  [self setSelected:![self isSelected]];

}


- (void)sendActionsForControlEvents:(UIControlEvents)controlEvents {
  [super sendActionsForControlEvents:controlEvents];

  // toggle state
  [self setSelected:![self isSelected]];

}


- (void)touchesEnded:(NSSet *)touches
           withEvent:(UIEvent *)event {

  [super touchesEnded:touches withEvent:event];
  // toggle state
  [self setSelected:![self isSelected]];
}

None of these methods are triggered. Any clues?

Answer 1

I could be barking up the wrong tree (pun partially intended), but I created a Swift project that does what I think you're asking for. I realize you're using ObjC, but for sake of time on my part I made it in Swift. In any case, it'll give you somewhere to start.

Here is the repo on GitHub: Click Here
--> Note: You'll need >= Xcode 6 to run the project.

A few things to note in the project:
1 - Be sure and connect the Button on Main.storyboard to the class you've created.
2 - In Swift, the class MyButton: UIButton is the line that implements UIButton for the class. I'm certain there's an ObjC equivalent, this Stack Overflow question may be helpful syntactically: Click Here

Hopefully some of this is helpful!

Good luck,
Kyle

Answer 2

My guess is that the first two aren't called because the button doesn't have any target s registered with selector s. The third not being called is a little surprising.

That being said, you should to try [self addTarget:self action:@selector(buttonTapped:) forControlEvents: UIControlEventsTouchUpInside] .

Answer 3

发生这种情况的唯一方法是，如果尚未在UIButton子类上调用addTarget 。