进度条渐变色

        // 进度条
        UIView *numView = [[UIView alloc] initWithFrame:CGRectMake(0, 27, kPreViewWith, 3)];
        numView.backgroundColor = kBorderColor;//kBorderColor
        [self addSubview:numView];

        //初始化渐变层
        self.gradientLayer = [CAGradientLayer layer];
        self.gradientLayer.frame = CGRectMake(0, 0, length, numView.bounds.size.height);
        [numView.layer addSublayer:self.gradientLayer];

        // 设置渐变颜色方向
        self.gradientLayer.startPoint = CGPointMake(0, 0.5);
        self.gradientLayer.endPoint = CGPointMake(1, 0.5);

        // 设定颜色组
        self.gradientLayer.colors = @[(__bridge id)kBeginRed.CGColor, (__bridge id)kEndRed.CGColor];

        //设定颜色分割点
        //        self.gradientLayer.locations = @[@(0.5f) ,@(1.0f) ];