IOS Quartz2D 通過UIColor產生圖片，

IOS Quartz2D 通過UIColor產生圖片，

普通產生

範例程式碼：

//這裡實現普通產生圖片的方法- (void)drawRect:(CGRect)rect {    CGRect cxRect = CGRectMake(0, 0, 100, 100);        UIGraphicsBeginImageContextWithOptions(cxRect.size, NO, 0);        [[UIColor redColor] setFill];        UIRectFill(cxRect);        UIImage * image = UIGraphicsGetImageFromCurrentImageContext();        UIGraphicsEndImageContext();        UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(20, 20, 100, 100)];        imageView.image = image;        [self addSubview:imageView];}

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漸層顏色產生

範例程式碼：

//這裡實現漸層顏色產生圖片的方法- (void)drawRect:(CGRect)rect {    CGRect cxRect = CGRectMake(0, 0, 1, 1);    UIGraphicsBeginImageContextWithOptions(cxRect.size, NO, 0);    CGContextRef context = UIGraphicsGetCurrentContext();    UIColor * beginColor = [UIColor greenColor];    UIColor * endColor = [UIColor redColor];    drawLinearGradient(context, cxRect, beginColor.CGColor, endColor.CGColor);    CGContextRestoreGState(context);        UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(20, 20, 100, 100)];        imageView.image = image;        [self addSubview:imageView];}void drawLinearGradient(CGContextRef context, CGRect rect, CGColorRef startColor, CGColorRef endColor){    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGFloat locations[] = { 0.0, 1.0 };        NSArray *colors = @[(__bridge id) startColor, (__bridge id) endColor];        CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) colors, locations);    CGPoint startPoint = CGPointMake(rect.size.width/2, 0);    CGPoint endPoint = CGPointMake(rect.size.width/2, rect.size.height/1.5);        CGContextSaveGState(context);    CGContextAddRect(context, rect);    CGContextClip(context);    CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);    CGContextSetStrokeColorWithColor(context, [[UIColor clearColor] CGColor]);}

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