+(CAGradientLayer *)gradientColorWithBounds:(CGRect)bounds startColorHexString:(NSString *)startColor endColorHexString:(NSString *)endColor {
CAGradientLayer *gradientLayer = [CAGradientLayer layer];
gradientLayer.colors = @[(__bridge id)[UIColor colorWithHexString:startColor].CGColor, (__bridge id)[UIColor colorWithHexString:endColor].CGColor];
gradientLayer.locations = @[@, @];
gradientLayer.startPoint = CGPointMake(, );
gradientLayer.endPoint = CGPointMake(1.0, 1.0);
gradientLayer.frame = bounds;
return gradientLayer;
}

以上代码就是比较自然的设置渐变色的方法，关于是否会自然润滑的渐变主要看 locations startPoint endPoint 3个属性的设置值

by:初光夫