Draw a simple circle uiimage
cgcontext, core-graphics, geometry, ios, uiimage
Solution
You need to include alpha channel into your bitmap: `UIGraphicsBeginImageContextWithOptions(..., NO, ...)` if you want to see what is behind the corners.
Problem
I try to make a 20x20 UIImage with a simple blue circle. I try with this function, but the result is a blue circle in a black square. How do I remove the black square around the circle? Function: ``` + (UIImage *)blueCircle { static UIImage *blueCircle = nil; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ UIGraphicsBeginImageContextWithOptions(CGSizeMake(20.f, 20.f), YES, 0.0f); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextSaveGState(ctx); CGRect rect = CGRectMake(0, 0, 20, 20); CGContextSetFillColorWithColor(ctx, [UIColor cyanColor].CGColor); CGContextFillEllipseInRect(ctx, rect); CGContextRestoreGState(ctx); blueCircle = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); }); return blueCircle; } ``` actual result: