CAGradientLayer不工作

Question

我创造了一个新项目。我链接了QuartzCore.framework并在ViewController.m中导入了<QuartzCore/QuartzCore.h>。

这是密码。

- (void)viewDidLoad {
    [super viewDidLoad];

    NSLog(@"view height %f", self.view.frame.size.height); // returns 667 on iPhone 6
    NSLog(@"view width %f", self.view.frame.size.width); // returns 375 on iPhone 6

    NSLog(@"layers count %lu", self.view.layer.sublayers.count); // returns 2

    // Gradient
    UIColor *colorOne = [UIColor blueColor];
    UIColor *colorTwo = [UIColor greenColor];
    NSArray *colorArray = @[colorOne, colorTwo];

    NSNumber *locationOne = [NSNumber numberWithFloat:0.0];
    NSNumber *locationTwo = [NSNumber numberWithFloat:1.0];
    NSArray *locationArray = @[locationOne, locationTwo];

    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.frame = self.view.frame;
    gradientLayer.colors = colorArray;
    gradientLayer.locations = locationArray;

    [self.view.layer insertSublayer:gradientLayer atIndex:0];
    //[self.view.layer insertSublayer:gradientLayer above:[self.view.layer.sublayers firstObject]]; // didn't work either

    NSLog(@"layers count %lu", self.view.layer.sublayers.count); //returns 3
}

我尝试将视图的背景色设置为clearColor，在viewDidAppear中调用它，但它们都没有工作。我真的不知道我错过了什么。谢谢你的帮助。

Answer 1

您的颜色数组应该是NSArray *colorArray = @[(id)colorOne.CGColor, (id)colorTwo.CGColor];，因为colors数组使用的是CGColorRef，而不是UIColor的，这已经够烦人的了-请参阅CGGradientLayer文档。