iOS RGB 颜色不正确？

Question

 UIGraphicsBeginImageContext(self.view.frame.size);
    [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 8.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 135.0,213.0,0.0,1.0);
    CGContextBeginPath(UIGraphicsGetCurrentContext());
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(),currentPoint.x, currentPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

我画一条线使用 RGB(135,213,0),RGB(135,213,0) 应该是 绿色。但是iOS显示黄线！！为什么？

Answer 1

您的值需要在 [0,1] 范围内。因此您需要将每个值除以 255。

CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 135.0/255.0,213.0/255.0,0.0,1.0);

Answer 2

将每个值除以 255 即 RGB(135/255,213/255,0)

Answer 3

最大值为 1.0，将每个参数除以 255.0