IOS 中view 添加阴影

       view.layer.shadowOffset =CGSizeZero;

       view.layer.shadowOpacity =0.75f;    //透明度

       view.layer.shadowRadius =10.0f;    //半径

       view.layer.shadowColor = [UIColorblackColor].CGColor;

       view.layer.shadowPath = [UIBezierPathbezierPathWithRect:self.loginbackgroundView.layer.bounds].CGPath;