iOS / Objective-C：更改图像视图的色彩

Question

I would like to change the color of an image view when the user touches it. I don't need it to change a great deal. However, I would like it to change to a shade of blue. I found the following code to change the gradient but it is not having any effect. I don't need a gradient, actually, only a tint. Would appreciate any suggestions.

 UIView *snapshot = [[UIImageView alloc] initWithImage:image];
        snapshot.layer.masksToBounds = NO;
          CAGradientLayer *gradient = [CAGradientLayer layer];

        gradient.colors = @[(id)[UIColor redColor].CGColor, (id)[UIColor blackColor].CGColor];

        [snapshot.layer insertSublayer:gradient atIndex:0];

Answer 1

You can try giving the UIImage a tint

UIImage *image = [[UIImage imageNamed:@"Your Image"] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
imageView.tintColor = [UIColor clearColor]; // Or any color really you'd like would work
imageView.image = newImage;

And then changing that tint when the user touches the image using a tap gesture recognizer

Answer 2

An easy and non-intrusive way is to add a translucent overlay to your image view. This can then be shown and hidden as the button is pressed and released.

- (void)indicatedImageViewPressed:(UIImageView *)imageView on:(BOOL)on {
    UIView *overlay = [imageView viewWithTag:1]; // See if already created
    if (overlay == nil) {
        overlay = [[UIView alloc] initWithFrame:imageView.bounds];
        overlay.tag = 1; // Mark view to find it next time
        overlay.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:0.3]; // Your color overlay goes here
        [imageView addSubview:overlay];
    }
    overlay.hidden = !on;
}