相机扫描区域外的阴影设置

- (void)setGrayLayerView{

    UIView *maskView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, kScreenWidth, kScreenHeight - 64)];
    
    maskView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.5];
    
    [self.view addSubview:maskView];
    
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, kScreenWidth, kScreenHeight)];
    
    [maskPath appendPath:[[UIBezierPath bezierPathWithRoundedRect:CGRectMake((kScreenWidth-200)/2, ((kScreenHeight-64)/2-100), 200, 200) cornerRadius:1] bezierPathByReversingPath]];
    
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    
    maskLayer.path = maskPath.CGPath;
    
    maskView.layer.mask = maskLayer;

}