Question

I have problems updating the image of an UIImageView from within a method that is called from a NSTimer.
It works within the viewDidLoad method where I do something like this
[imageView setImage:[self getNextImage]];

later on I do

NSTimer* readTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(readSource:) userInfo:nil repeats:NO];

[readTimer fire];

that works and the readSource method gets called.
There I put this code:

UIImageView* tempImageView = (UIImageView*)[containerView viewWithTag:nextDefragSourcePosition ];

That returns exactly the imageView I want to have –
but the following line does not change the image of the UIImageView

[tempImageView setImage:dataBeingReadImage];

Any ideas ? Thanks in advance.
Heiko

Answer 1

You are aware that you are updating the GUI from a different thread than where the UIImageView is created? You can execute selectors on the main thread to work around this problem.

Just take a look at the performSelectorOnMainThread method. Just call that from the method that gets called when your NSTimer triggers (readSource:) and supply it with the image you want to display. Then just update the UIImageView from THAT selector (not the readSource one) and it SHOULD work.

There really isn’t that much code for me to go on.