Question

我在故事板上绘制UILabel时遇到了麻烦;它总是空白的。标签被定义为属性self.rainbowCircle。以下是我的视图控制器中的设置：

self.rainbowCircle.layer.name = @"Rainbow Layer";
self.rainbowCircle.layer.delegate = self;
[self.rainbowCircle.layer setNeedsDisplay];

这里是drawLayer：inContext：

- (void) drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx
{
    CGContextSaveGState(ctx);
    if ([layer.name isEqualToString:@"Rainbow Layer"]) {
        NSLog(@"here");
        NSArray *rainbowColorsArray = [NSArray arrayWithObjects:
                                       (id)[UIColor colorWithHue:0.0                 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       (id)[UIColor colorWithHue:1.0*360.0/6.0/360.0 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       (id)[UIColor colorWithHue:2.0*360.0/6.0/360.0 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       (id)[UIColor colorWithHue:3.0*360.0/6.0/360.0 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       (id)[UIColor colorWithHue:4.0*360.0/6.0/360.0 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       (id)[UIColor colorWithHue:5.0*360.0/6.0/360.0 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       (id)[UIColor colorWithHue:1.0                 saturation:1.0 brightness:1.0 alpha:1.0].CGColor,
                                       nil];
        CGColorSpaceRef deviceRGB = CGColorSpaceCreateDeviceRGB();
        CGGradientRef gradient    = CGGradientCreateWithColors(deviceRGB, (__bridge CFArrayRef) (rainbowColorsArray), NULL);
        CGContextDrawRadialGradient(ctx, gradient, self.rainbowCircle.center, 0.0, self.rainbowCircle.center, self.rainbowCircle.bounds.size.width/2.0, kCGGradientDrawsBeforeStartLocation);
        CGColorSpaceRelease(deviceRGB);
        CGGradientRelease(gradient);
    } else {
        [self drawPalette:self.currentPalette inLayer:layer inContext:ctx];
    }
    CGContextRestoreGState(ctx);
}

我已经盯着这个很长一段时间了，只是看不到我错过的东西。 NSLog确实显示了。任何指导意见。

Answer 1

您无法更改UIView图层的委托，它必须是视图本身

drawLayer：UILabel上的inContext

1 个答案: