彩虹颜色渲染图层

//调用渲染

[self.view.layer addSublayer:[self shadowLayer]];

- (CAGradientLayer *)shadowLayer

{

CAGradientLayer *newShadow = [[CAGradientLayer alloc] init] ;

newShadow.frame =  CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

//添加渐变的颜色组合

newShadow.colors = [NSArray arrayWithObjects:(id)[UIColor redColor].CGColor,(id)[UIColor greenColor].CGColor,(id)[UIColor magentaColor].CGColor,(id)[UIColor yellowColor].CGColor,(id)[UIColor blueColor].CGColor,(id)[UIColor orangeColor].CGColor,nil];

return newShadow;

}