iOS放射渐进视图

iOSRadioGradient.m

CGContextRef context = UIGraphicsGetCurrentContext(); 
size_t num_locations = 2;
CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB(); 
CGFloat components[8] = {1,1,1,1, // 中心颜色（r， g， b， alpha） 
                        .2,.2,.2,1 // 边缘颜色};
                        CGFloat locations[2] = {0,1};
CGGradientRef gradient = CGGradientCreateWithColorComponents(rgb, components, locations, num_locations);
CGColorSpaceRelease(rgb);
CGRect bounds = self.bounds; 
CGPoint center = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds)); // 中心发散渐进 
CGContextDrawRadialGradient(context, gradient, center, 0, center, bounds.size.width, kCGGradientDrawsAfterEndLocation);
CGGradientRelease(gradient);