释放双眼，带上耳机，听听看~！
CAGradientLayer *gradient = [CAGradientLayerlayer];
gradient.frame =self.view.bounds;
gradient.colors = [NSArrayarrayWithObjects:(id)[[UIColorredColor] CGColor],(id)[[UIColorwhiteColor] CGColor],nil,nil];
[self.view.layerinsertSublayer:gradient atIndex:0];