CoreGraphics漸變不顯示在iOS4上

Question

我有以下代碼在iOS5上正常工作。

//// Abstracted Graphic Attributes 
NSString* textContent = [NSString stringWithFormat:@"%i",[myAnnotation.annotations count]]; 

//// General Declarations 
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
CGContextRef context = UIGraphicsGetCurrentContext(); 

//// Gradient Declarations 
NSArray* gradient3Colors = [NSArray arrayWithObjects: 
          (id)[UIColor lightGrayColor].CGColor, 
          (id)[UIColor darkGrayColor].CGColor, nil]; 
CGFloat gradient3Locations[] = {0, 1}; 
CGGradientRef gradient3 = CGGradientCreateWithColors(colorSpace, (CFArrayRef)gradient3Colors, gradient3Locations); 


//// Oval Drawing 
UIBezierPath* ovalPath = [UIBezierPath bezierPathWithOvalInRect: CGRectMake(0.5, 0.5, 34, 34)]; 
CGContextSaveGState(context); 
[ovalPath addClip]; 
CGContextDrawRadialGradient(context, gradient3, 
          CGPointMake(17.5, 17.5), 10, 
          CGPointMake(17.5, 17.5), 30, 
          kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation); 
CGContextRestoreGState(context); 

[[UIColor blackColor] setStroke]; 
ovalPath.lineWidth = 0.5; 
[ovalPath stroke]; 


//// Text Drawing 
CGRect textFrame = CGRectMake(0, 7.0, 35, 20); 
[[UIColor whiteColor] setFill]; 
[textContent drawInRect: textFrame withFont: [UIFont fontWithName: @"HelveticaNeue" size: [UIFont systemFontSize]] lineBreakMode: UILineBreakModeWordWrap alignment: UITextAlignmentCenter]; 

//// Cleanup 
CGGradientRelease(gradient3); 
CGColorSpaceRelease(colorSpace); 

這繪製了一個帶有灰色漸變的圓，中間是一個數字。在iOS5上，這顯示正確。在iOS4上，它不會錯誤或提醒我使用錯誤的API和一切，但灰色漸變已被繪製！任何想法呢？

Answer 1

好吧，iOS4出於某種原因不喜歡定義的顏色。

使用以下修復它。

UIColor* myLightGrey = [UIColor colorWithRed: 0.66 green: 0.66 blue: 0.66 alpha: 1]; 
UIColor* myDarkGrey = [UIColor colorWithRed: 0.33 green: 0.33 blue: 0.33 alpha: 1]; 

//// Gradient Declarations 
NSArray* gradient3Colors = [NSArray arrayWithObjects: 
          (id)myLightGrey.CGColor, 
          (id)myDarkGrey.CGColor, nil]; 
CGFloat gradient3Locations[] = {0, 1};