我尝试如下子类化UITextField以将自定义rightView实现为清除按钮:-(void)drawRect:(CGRect)rect{[self.layersetBackgroundColor:[[UIColorcolorWithRed:20.0/255.0green:20.0/255.0blue:20.0/255.0alpha:1]CGColor]];[self.layersetCornerRadius:15.0];UIImage*imgClear=[UIImageimageNamed:@"btnClear"];CGSizeiSize=[imgClearsize];UIButt