2) Import QuartzCore.h file to implementation file.
3) #define kRectArmLength 24.0 (Not necessary, as you can decide while initializing label with frame)
//Label will be a square (equal width & height)
UILabel *lblCircle = [[UILabel alloc] initWithFrame:CGRectMake(10,20, kRectArmLength, kRectArmLength)];
//set corner radius just half of the square arm length
lblCircle.backgroundColor = [UIColor redColor];
[self.view adsSubview: lblCircle];