ios UIView 添加陰影

#import <QuartzCore/QuartzCore.h>" to header file

self.layer.masksToBounds = NO; self.layer.cornerRadius = 8; // if you like rounded corners 

self.layer.shadowOffset = CGSizeMake(-15, 20); 

self.layer.shadowRadius = 5;  
 self.layer.shadowOpacity = 0.5;  

 This will slow down the application. Adding the following line can improve performance as long as your view is visibly rectangular: 

self.layer.shadowPath = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;