Estou implementandoUIButton e meuUIControlEventTouchUpInside evento não dispara, mesmo queUIControlEventTouchDown dispara.

UIButton *btnClose = [UIButton buttonWithType:UIButtonTypeCustom];
NSString *filePathImage = @"img.png";
NSString *filePathImageTap = @"img-tap.png";
UIImage *buttonImage = [UIImage imageWithContentsOfFile:filePathImage];
UIImage *buttonImageTap = [UIImage imageWithContentsOfFile:filePathImageTap];
[btnClose setImage:buttonImage forState:UIControlStateNormal];
[btnClose setImage:buttonImageTap forState:UIControlStateSelected];
[btnClose setImage:buttonImageTap forState:UIControlStateHighlighted];      
[btnClose addTarget:self action:@selector(close:) forControlEvents:UIControlEventTouchUpInside];    
[self.view addSubview:btnClose];