v.backgroundColor=[UIColor yellowColor];
//v.layer.masksToBounds=YES;這行去掉
v.layer.cornerRadius=10;
v.layer.shadowColor=[UIColor redColor].CGColor;
v.layer.shadowOffset=CGSizeMake(10, 10);
v.layer.shadowOpacity=0.5;
v.layer.shadowRadius=5;
[self.view addSubview:v];
效果如下