self.backView.clipsToBounds = YES;

self.backView.layer.cornerRadius = 6.f;

    self.backView.layer.shadowColor = [UIColor blackColor].CGColor;//shadowColor阴影颜色

    self.backView.layer.shadowOffset = CGSizeMake(6,6);//shadowOffset阴影偏移,x向右偏移4，y向下偏移4，默认(0, -3),这个跟shadowRadius配合使用

    self.backView.layer.shadowOpacity = 0.5;//阴影透明度，默认0

    self.backView.layer.shadowRadius = 4;//阴影半径，默认3

//    self.backView.clipsToBounds = YES;

self.backView.layer.cornerRadius = 6.f;

self.backView.layer.shadowColor = [UIColor blackColor].CGColor;

self.backView.layer.shadowOffset = CGSizeMake(5, 5);

self.backView.layer.shadowOpacity = 0.5;

self.backView.layer.shadowRadius = 6.f;