Change image when a button is clicked using Objective-C

Question

I am trying to switch between two different images when clicking on a button. Below is the code I wrote so far. However, this will only display one image and not toggle between them.

-(IBAction)show {

    BOOL img = true;

    if (img = true) {
    UIImage *img1 = [UIImage imageNamed:@"UnCheck.png"];
    [imageview setImage:img1];
        }
    else {
        UIImage *img = [UIImage imageNamed:@"Check.png"];
        [imageview setImage:img];
    }
}

Possible duplicate of [Setting an image for a UIButton in code](https://stackoverflow.com/questions/1469474/setting-an-image-for-a-uibutton-in-code) Just change the state to your required state. — Rakesha Shastri, Sep 01 '18 at 08:08
If you set a true Bool inside the first line of the method it runs always the code into the if. — Kerberos, Sep 01 '18 at 08:11
@kerberos The problem I've got is that the code always run else if the if statement is set to "false" — Teo Ohlsson, Sep 01 '18 at 08:23

score 1 · Accepted Answer · answered Sep 01 '18 at 08:28

You have a couple of issues with your code:

First, img is a local variable inside your tap handler, so each time that function runs, it will be set to true.

Second, your if statement actually contains an assignment (=) instead of a comparison (==), so even if img wasn't already true it would be when you execute the if statement.

All of this means that your image is always going to be UnCheck.png.

You need to use a property, outside the function, so that the state is tracked properly. img is also a pretty poor variable name, checked or isChecked is probably better.

Then your button handler method simply needs to toggle this property and set the appropriate image.

@property BOOL isChecked;

-(IBAction)show {
    self.isChecked = !self.isChecked;

    NSString *imageName = self.isChecked ? @"Check.png":@"UnCheck.png";
    UIImage *img = [UIImage imageNamed:imageName];
    [imageview setImage:img];
 }

You can refactor it a little more by using image isHighlighted property too. Add following code where `imageview` initialized. `UIImageView(image: UIImage?, highlightedImage: UIImage?)` And use below in your `(IBAction)show` imageview.isHighlighted = self.isChecked — Satish, Sep 01 '18 at 09:43

Change image when a button is clicked using Objective-C

1 Answers1