Using UITextAlignmentCenter with #selector - iphone

Question

I'm trying to change the alignment of a UILabel on the main thread like this
[updateLabel performSelectorOnMainThread:#selector(setTextAlignment:) withObject:UITextAlignmentCenter waitUntilDone:YES];
However this generates a "makes pointer from integer without cast error. What's the correct way to do this?

Answer 1

This is not going to work because UITextAlignmentCenter is not a pointer to an object, but a simple integer. A solution is to implement an own method on the view controller that sets the alignment to center via updateLabel.textAlignment = UITextAlignmentCenter; and calling [yourViewController performSelectorOnMainThread:#selector(setUpdateLabelTextAlignmentToCenter) withObject:nil waitUntilDone:YES];

Answer 2

You're passing a raw integer to "withObject" instead of an object, that's why you're getting the error. Instead, you could call a selector of your own on the main thread that does the job for you, passing in a dictionary or array containing the UILable object to change, and the new alignment value packaged up as a NSNumber:
- (void) changeLabelAlignment:(NSArray *)argsArray
{
UILabel *lbl = [argsArray objectAtIndex:0];
int alignment = [[argsArray objectAtIndex:1] intValue];
lbl.textAlignment = alignment;
}
calling it this way:
...
NSArray *argsArray = [NSArray arrayWithObjects:label, [NSNumber numberWithInt: UITextAlignmentCenter], nil];
[myClassObject performSelectorOnMainThread:#selector(changeLabelAlignment:)
withObject:argsArray
waitUntilDone:YES];