UIButton nil - IOS - iphone

Question

I have the following in my viewdidload:
//Start/Pause Button
UIButton *buttonStart = [UIButton buttonWithType: UIButtonTypeCustom];
buttonStart.frame = CGRectMake(10,100,100,45);
[buttonStart setBackgroundImage:[UIImage imageNamed:#"pause.png"] forState:UIControlStateNormal];
[buttonStart addTarget:self action:#selector(pausePlayButtonTouched) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview: buttonStart];
my selector method:
[self.buttonStart setBackgroundImage:[UIImage imageNamed:#"start.png"] forState:UIControlStateNormal];
NSLog(#"%#", self.buttonStart);
null is being logged to the console. And needless to say, the image for the button is not being changed.
What is wrong with my thinking?
btw buttonStart is being synthesized and has its own property (retain).

Answer 1

You are using both, an instance variable self.buttonStart accessed via property and a local variable buttonStart. Remove the declaration of that button from your implementation file and change the first line towards this:
self.buttonStart = [UIButton buttonWithType: UIButtonTypeCustom];

Answer 2

No need of property for buttonStart.Add target like this:
[buttonStart addTarget:self action:#selector(pausePlayButtonTouched:) forControlEvents:UIControlEventTouchUpInside];
Now your selected method would be:
-(void)pausePlayButtonTouched:(id)sender
{
UIButton *btnPaused = sender;
NSLog(#"%#", btnPaused);
[btnPaused setBackgroundImage:[UIImage imageNamed:#"start.png"] forState:UIControlStateNormal];
}

Answer 3

Are you assigning self.buttonStart anywhere? Did you mean
self.buttonStart = [UIButton buttonWithType: UIButtonTypeCustom];
instead of
UIButton *buttonStart = [UIButton buttonWithType: UIButtonTypeCustom];

Answer 4

You should drop the '.png' tag from your filename, i.e. "pause", not "pause.png".

Answer 5

As far as I can see the assignment of buttonStart is missing.
Did you set self.buttonStart = buttonStart; ?
declaring UIButton *buttonStart = ... will shadow (in your local context) any created member that was created by #property (nonatomic, reatin) UIButton *buttonStart; (if you use LLVM 4.0+ your property declaration will create "UIButton *_buttonStart" as a member)