边界的渐变背景图层

Created: November-22, 2018

+ (CALayer *)gradientBGLayerForBounds:(CGRect)bounds colors:(NSArray *)colors
{
    CAGradientLayer * gradientBG = [CAGradientLayer layer];
    gradientBG.frame = bounds;
    gradientBG.colors = colors;
    return gradientBG;
}