在iOS 6中, - [UITextField becomeFirstResponder]在-viewWillAppear中不起作用:

Question

在iOS 5.1和iOS 5.0中它可以工作,但在iOS 6.0中键盘不显示.

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    UITextField *textField = self.emailAddressTextField;
    [textField becomeFirstResponder];
}

现在我把逻辑移到了-viewDidAppear:.

// This works but is not desirable.
- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    UITextField *textField = self.emailAddressTextField;
    [textField becomeFirstResponder];
}

这有效,但不可取.在加载视图后显示键盘上滑动画.

我希望键盘能够出现,因为从左到右的动画显示了导航控制器中加载的视图.

有人知道如何在iOS 6中显示视图时加载键盘吗？

更新

根据@ Duck的反馈,我做了一些测试.这似乎特定于UITableViewCells中包含的UITextFields.

有没有人有什么建议？

第一个解决方案

所以完整的描述.这是一个带有两个静态单元格(电子邮件和密码)的表格视图.视图中有一个分配了页脚视图的登录按钮.这两个单元格中包含一个文本字段,并且是自定义类型SICOTextFieldCell.

我的解决方案是在登录按钮后面放置一个假文本字段(在表格页脚视图中).

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    UITextField *textField = self.SICO_fakeTextField;
    [textField becomeFirstResponder];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    UITextField *textField = self.SICO_emailAddressTextField;
    [textField becomeFirstResponder];
}

新解决方案

基于@stm的答案,我提出了一个新的(优越的？)解决方案.

我的解决方案是致电-selectRowAtIndexPath:animated:scrollPosition:.-[SICOTextFieldCell setSelected:animated:],这是一个自定义表视图单元格,调用[self.textField becomeFirstResponder]它可以神奇地正确绘制键盘.它仍然是一个黑客,但它是一个更干净的黑客.

@interface SICOLogInViewController ()
@property (readonly, nonatomic) UITextField *SICO_emailAddressTextField;
@property (readonly, nonatomic) UITextField *SICO_passwordTextField;
@end

@implementation SICOLogInViewController

- (IBAction)logIn
{
    // Controller Details
}

#pragma mark Private

- (UITextField *)SICO_textFieldForRowAtIndexPath:(NSIndexPath *)indexPath
{
    SICOTextFieldCell *cell = (SICOTextFieldCell *)[self.tableView cellForRowAtIndexPath:indexPath];
    return cell.textField;
}

#pragma mark View lifecycle

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self.tableView selectRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]
                                animated:NO scrollPosition:UITableViewScrollPositionTop];
}

#pragma mark UITextFieldDelegate

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    switch (textField.returnKeyType) {
        case UIReturnKeyGo:   [self logIn];                                       break;
        case UIReturnKeyNext: [self.SICO_passwordTextField becomeFirstResponder]; break;
        default: break;
    }
    return YES;
}

#pragma mark Properties

- (UITextField *)SICO_emailAddressTextField
{
    return [self SICO_textFieldForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];
}

- (UITextField *)SICO_passwordTextField
{
    return [self SICO_textFieldForRowAtIndexPath:[NSIndexPath indexPathForRow:1 inSection:0]];
}

@end

Answer 1

尝试在创建单元格后在cellForRowAtIndexPath方法中调用它,或者在包含该textField的tableViewCell的viewWillAppear中调用它.

如果这给你相同的结果,你仍然希望键盘出现之前,我会使用"假"textField在开头显示键盘.我的猜测是你的textField还没有在viewWillAppear之前添加.