iOS 按钮渐变色

 _signBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        _signBtn.layer.cornerRadius = 20;
        _signBtn.layer.masksToBounds = YES;
        _signBtn.frame = CGRectMake(70, 200, kScreen_Width-160, 36);
       
        CAGradientLayer *gradientLayer =  [CAGradientLayer layer];
        gradientLayer.frame = CGRectMake(0, 0, kScreen_Width-160, 36);
        gradientLayer.startPoint = CGPointMake(0, 0);
        gradientLayer.endPoint = CGPointMake(1, 0);
        gradientLayer.locations = @[@(0.5),@(1.0)];//渐变点
        [gradientLayer setColors:@[(id)[[UIColor colorWithHexString:@"#2D6DFF"] CGColor],(id)[[UIColor colorWithHexString:@"#349AFF"] CGColor]]];//渐变数组
        [_signBtn.layer addSublayer:gradientLayer];
        [_signBtn setTitle:@"签到领积分" forState:UIControlStateNormal];
        _signBtn.titleLabel.font = [UIFont systemFontOfSize:14];
        [_signBtn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal]; _signBtn = [UIButton buttonWithType:UIBu