UITextField rightViewMode奇怪的行为

Question

我将自定义清除按钮(UIButton)添加到UITextField作为rightView,但是我发现viewMode上有一些奇怪的行为.尽管设置了视图模式,但它似乎不像普通的清除按钮那样显示.示例代码如下:

UITextField *f = [[[UITextField alloc] init] autorelease];
f.frame = CGRectMake(0, 0, 300, 44);
f.backgroundColor = [UIColor clearColor];
f.textColor = [UIColor whiteColor];

f.clearButtonMode = UITextFieldViewModeNever;

UIImage *image = [UIImage imageNamed:@"Image.png"];

UIButton *b = [UIButton buttonWithType:UIButtonTypeCustom];
b.frame = CGRectMake(0, 0, image.size.width, image.size.height);
[b setImage:image forState:UIControlStateNormal];

f.rightView = b;
f.rightViewMode = UITextFieldViewModeWhileEditing;

该按钮在以下状态下正确显示:

• 显示聚焦时没有文字
• 在聚焦和打字时显示
• 没有焦点时隐藏

但是,如果文本字段已有内容,并且您将焦点切换到它,则不会显示清除按钮.要让它再次显示,您必须删除所有文本,并来回切换焦点.

我还没有找到任何有这个问题的人,所以一直在这个问题上摸不着头脑.任何光线都非常受欢迎.

Answer 1

这修复了错误:

- (BOOL)becomeFirstResponder
{
    BOOL ret = YES ;

    ret = [super becomeFirstResponder] ;

    if( ret && ( _setupClearButtonMode == UITextFieldViewModeWhileEditing ) )
        self.rightViewMode = UITextFieldViewModeAlways ;

    return ret ;
}

- (BOOL)resignFirstResponder
{
    BOOL ret = YES ;

    ret = [super resignFirstResponder] ;

    if( ret && ( _setupClearButtonMode == UITextFieldViewModeWhileEditing ) )
        self.rightViewMode = UITextFieldViewModeWhileEditing ;

    return ret ;
}

在UITextField的子类中,在init上设置var _setupClearButtonMode.