UIButton as switch

问题

I'm trying to create a push-on-push-off-like button with custom images in Xcode4 for iOS. The code I'm using is

- (IBAction)btnAll:(id)sender
{
    UIButton *button = (UIButton *)sender;
    button.selected = !button.selected;
}

That works fine for now. But my problem is, that when I'm toggling on, I press it on, then it is popping off again and then finally on. The app works, but that is really ugly, though.

I firstly set the "highlighted" image to on. So when I highlight the button, it is on and that popping to on. That works fine. But when I turn it off again, the problem is the same, in the reverse direction.

I tried to put that code:

- (IBAction)btnAll:(id)sender
{
    UIButton *button = (UIButton *)sender;
    if(button.selected)
    {
        [button setImage[UIImage imageNamed@"off.png"] forState:UIControlStateHighlighted];
    }
    else
    {
        [button setImage[UIImage imageNamed@"on.png"] forState:UIControlStateHighlighted];
    }
    button.selected = !button.selected;
}

But as long button.selected = !button.selected there is no difference. So it won't make any change.

I also tried to trigger the IBAction on »Touch Down« but you can imagine how frustrating this will look like.

Has anybody got a solution for that problem? Did anybody struggle with that one too?

Greets, thanks a lot Julian

回答1:

I've had a similar problem to this before, the button works a little strangely when tapping. Try this code and let me know if it works

    UIButton *button = (UIButton *)sender;
    if(button.selected)
    {
        [button setImage:[UIImage imageNamed:@"off.png"] forState:UIControlStateHighlighted];
        [button setImage:[UIImage imageNamed:@"off.png"] forState:UIControlStateSelected];
        [button setImage:[UIImage imageNamed:@"off.png"] forState:UIControlStateHighlighted | UIControlStateSelected];
    }
    else
    {
        [button setImage:[UIImage imageNamed:@"on.png"] forState:UIControlStateHighlighted];
        [button setImage:[UIImage imageNamed:@"on.png"] forState:UIControlStateSelected];
        [button setImage:[UIImage imageNamed:@"on.png"] forState:UIControlStateHighlighted | UIControlStateSelected];
    }
    button.selected = !button.selected;

    If (button.selected) {
      [button setImage:[UIImage imageNamed:@"on.png"] forState:UIControlStateNormal];
    } else {
      [button setImage:[UIImage imageNamed:@"off.png"] forState:UIControlStateNormal];
    }

When you tap and hold on a button the state is actually Highlighted & Selected so you need an image for both Highlight and selected state.

回答2:

Don't manually switch the images around, just set the selected state's image in Interface Builder and swap the selected property over when the button is tapped.

回答3:

Agree with Jim, your code needs little modification as below...

[button setImage[UIImage imageNamed@"off.png"] forState:UIControlStateNormal];
[button setImage[UIImage imageNamed@"on.png"] forState:UIControlStateSelected];

回答4:

Have two buttons created.

place buttons one above one.

Can set Default & Selected images using Custom Button option in design builder.

-(void)firstButtonClicked {

firstButton.hidden = YES;
secondButton.hidden = NO;

}

-(void)secondButtonClicked {

firstButton.hidden = NO;
secondButton.hidden = YES;

}

回答5:

@Jim - when do u switch the isSelected state? isHighlighted gets called twice for every press. My hacked version of UIButton switch below : -

class ButtonSwitch: UIButton {

  override func sendAction(_ action: Selector, to target: Any?, for event: UIEvent?) {
    if allControlEvents == .touchUpInside {
      isSelected.toggle()
    }
    super.sendAction(action, to: target, for: event)
  }
}

来源：https://stackoverflow.com/questions/8571485/uibutton-as-switch