Iphone How to make context background transparent?

Question

CALayer *sublayer = [CALayer layer];
/*sublayer.backgroundColor = [UIColor blueColor].CGColor;
sublayer.shadowOffset = CGSizeMake(0, 3);
sublayer.shadowRadius = 5.0;         


        

Answer 1

UIGraphicsBeginImageContextWithOptions(CGSizeMake(400, 400), NO, 1);

Setting this argument to NO solves my problem.