重载UIView子类中的drawRect:方法,自己在drawRect:里面画倒影
CGContextRef context = UIGraphicsGetCurrentContext();
UIFont *myFont = [UIFont systemFontOfSize:17];
CGContextSetShadow(context, CGSizeMake(5, 5), 2);
[@"需要倒影的文字" drawAtPoint:CGPointMake(50, 50) withFont:myFont];