iOS 設定視圖陰影

第一種：

//設定四周陰影
- (void)setShadowLayer{
    self.layer.masksToBounds = false;
    self.layer.shadowOffset = CGSizeMake(0, -2);//設定陰影偏移
    self.layer.shadowOpacity = 陰影透明度;
    self.layer.shadowRadius = 陰影弧度;
    self.layer.shadowColor = 陰影顔色.CGColor;
}           

第二種：

/**
 設定頂邊陰影

 @param shadowColor 陰影顔色
 @param radious 陰影圓角
 @param offset 陰影偏移量
 */
- (void)setShadowLayer:(UIColor *)shadowColor shadowRadius:(CGFloat)radious shadowOffset:(CGFloat)offset{
    CGSize size = self.bounds.size;
    self.layer.frame = self.bounds;
    self.layer.shadowOpacity = 1;
    self.layer.shadowColor = shadowColor.CGColor;
    self.layer.shadowOffset = CGSizeMake(0, offset);
    
    CGRect rect = CGRectMake(-offset, offset - radious/2, size.width+2*offset, radious);
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:radious];
    self.layer.shadowPath = path.CGPath;
}