iOS view添加阴影

四边阴影

UIView* view=[UIView new];                               
view.layer.shadowColor = [UIColor lightGrayColor].CGColor;
view.layer.shadowOffset = CGSizeMake(0,0.5);
view.layer.shadowOpacity = 0.6;
view.layer.shadowRadius = 1.0;
view.clipsToBounds = NO;  ``

上边阴影

- (void)addShadowToView:(UIView *)theView withColor:(UIColor *)theColor {
    
    theView.layer.shadowColor = theColor.CGColor;
    theView.layer.shadowOffset = CGSizeMake(0,0);
    theView.layer.shadowOpacity = 0.5;
    theView.layer.shadowRadius = 5;
    // 单边阴影 顶边
    float shadowPathWidth = theView.layer.shadowRadius;
    CGRect shadowRect = CGRectMake(0, 0, theView.bounds.size.width, shadowPathWidth);//0-shadowPathWidth/2.0
    UIBezierPath *path = [UIBezierPath bezierPathWithRect:shadowRect];
    theView.layer.shadowPath = path.CGPath;
    
}

下边阴影

- (void)addShadowToView:(UIView *)theView withColor:(UIColor *)theColor {
    
    theView.layer.shadowColor = theColor.CGColor;
    theView.layer.shadowOffset = CGSizeMake(0,0);
    theView.layer.shadowOpacity = 0.5;
    theView.layer.shadowRadius = 5;
    // 单边阴影 顶边
    float shadowPathWidth = theView.layer.shadowRadius;
    CGRect shadowRect = CGRectMake(0, 40, theView.bounds.size.width, shadowPathWidth);//0-shadowPathWidth/2.0
    UIBezierPath *path = [UIBezierPath bezierPathWithRect:shadowRect];
    theView.layer.shadowPath = path.CGPath;
    
}

以此类推，可以设置阴影的方向

注释：控制shadowRect的坐标是控制阴影位置的关键，而设置view.clipsToBounds = NO;  这个属性为no是必须的，不然阴影不会显示