iOS 渐变色设置

CAGradientLayer *gradationLayer = [CAGradientLayer layer];

gradationLayer.frame = self.submitBtn.bounds;

    gradationLayer.colors = @[

        ( __bridge id)[UIColor colorWithRed:78/255.0 green:162/255.0 blue:245/255.0 alpha:1.00].CGColor,

        ( __bridge id)[UIColor colorWithRed:43/255.0 green:202/255.0 blue:228/255.0 alpha:1.00].CGColor,

        ];

    gradationLayer.startPoint = CGPointMake(0, 0);

    gradationLayer.endPoint = CGPointMake(1, 1);

    [self.submitBtn.layer addSublayer:gradationLayer];