如何在iOS中单击按钮时更改按钮的图像

Question

Confession: I have been through every possible link I could find, but unfortunately none work for me.

I am creating buttons dynamically. When a button is selected, it should change the color of the selected button and the rest should remain the default color. This way, the user can identify which button is selected.

Suppose there are 3 buttons: all blue in color, and when I select the first one, it should change to white and other two should remain blue. When I select the second, the first one should go back to blue and the second should now be white.

btnCounts data I am fetching from server and would vary.

  -(void)createButtons{
    for (int i=0; i<btnCounts; i++) {
       UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
       [btn setTag:i];
       [btn setFrame:CGRectMake(xVal, 0, width/btnCounts, 40)];
      // [btn setImage:[UIImage imageNamed:@"btn_image.png"] forState:UIControlStateNormal];
       [btn setBackgroundImage:[UIImage imageNamed:@"blue.png"] forState:UIControlStateNormal];
       [btn setBackgroundImage:[UIImage imageNamed:@"white.png"] forState:UIControlStateSelected];
       [btn setTitle:name forState:UIControlStateNormal];
       [btn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
       [btn addTarget:self action:@selector(btnClicked:) forControlEvents:UIControlEventTouchUpInside];
       [scrV addSubview:btn];
       xVal += self.view.frame.size.width/btnCounts+1;
     }
 }

Now, in btnClicked: method I am passing the button as a parameter, so that I can use selected button.

 -(void)btnClicked:(UIButton *)button
 {
     int tag = (int)button.tag;
     //...
 }

Please help me to find what I am missing here.

Thanks.

Answer 1

Create an instance UIButton variable to house the selected button so that you can deselect it when the next button is tapped. If you only pass the currently-tapped button to your btnClicked: method, you won't know which button to deselect (if any).

@implementation ClassName {
    UIButton *previousButton;
}

...

- (void)btnClicked:(UIButton *)button
{
    if(previousButton)
        [previousButton setBackgroundColor:[UIColor blueColor]];

    previousButton = button;

    [button setBackgroundColor:[UIColor whiteColor]];

    // do whatever else you need to do here
}

Answer 2

For that you need to store selected button in temporary object.

Create button in interface(.h) file:

UIButton *selectedButton;

Than add following line in -(void)createButtons method before for loop.

selectedButton = nil;

for() {...}

Here selectedButton is set to nil because initially none of the buttons are selected.

And finally replace your -(void)btnClicked:(UIButton *)button method with following method.

-(void)btnClicked:(UIButton *)button {
    if(selectedButton) {
        selectedButton.selected = NO;
    }

    button.selected = YES;
    selectedButton = button;
}

If you want to make any button initially selected than assign that button to selectedButton like in btnClicked method.