Flashing UIImage (overlaying as a pretend button)

[TrueScot]

I'm trying to use a UIImage as a button which gives the impression of it being turned on then off again within about half a second. This works fine if I switch it on but if I want to switch it off again (by including removeFromSuperview) it doesn't switch on at all. I have a short loop in there to prevent it switching on and off so fast I can't see it but it doesn't switch on at all. I've tried it with and without the [flashingButton release]. Is there something I'm misunderstanding here? Can I addSubview and removeFromSuperView at the same time even with a short delay?



if ( some conditional statements in here .......) {

UIImage *estimateButton1 = [UIImage imageNamed:@"FlashingButton.png"];
flashingButton = [[UIImageView alloc] initWithImage:flashingButton1];
flashingButton.frame = CGRectMake (146,8,165,30);
[self.view addSubview:flashingButton];
// [flashingButton release];


// short loop in here to delay turning the button off

[self.flashingButton removeFromSuperview];

[kelvinkao]

Whoa! Please don't do something like this.

What's happening here is that you are trying to add a view. And then you have a loop to block the execution of EVERYTHING. So during that time, your app can't do anything (such as showing the view?) And then once the loop is over, you remove the view. So nothing ever shows.

When you have the loop there to waste time, nothing is getting done. This is bad, just like sleeping the main thread. What you want to do instead is add the view. And then you set an NSTimer to fire later. When it fires, you hide the view. Or you can do it with performSelector withDelay methods. Just don't block the execution of the whole app! (Because the app will freeze during that time, and when it goes on for too long, the OS will even kill it!)

[mouser58907]

Why not just use a UIButton with an image instead of using a UIImage as a button. Also, instead of removing it from superview, if its going to come back shortly afterwords, just set hidden = YES for the button.