如何使UITextField首先选择全部，然后以编程方式进行编辑？

当用户点击所选文本时，这可以防止出现弹出窗口。

要允许第一次点击始终选择所有文本，并取消第二次点击，请将您的当前代码保留在textFieldDidBeginEditing方法中，并扩展UITextField至override canPerformAction:withSender:，以防止出现弹出窗口，如下所示：

UITextField子类

- (BOOL) canPerformAction:(SEL)action withSender:(id)sender {
    /* Prevent action popovers from showing up */

    if (action == @selector(paste:)
        || action == @selector(cut:)
        || action == @selector(copy:)
        || action == @selector(select:)
        || action == @selector(selectAll:)
        || action == @selector(delete:)
        || action == @selector(_define:)
        || action == @selector(_promptForReplace:)
        || action == @selector(_share:) )
    {
        //Get the current selection range
        UITextRange *selectedRange = [self selectedTextRange];

        //Range with cursor at the end, and selecting nothing
        UITextRange *newRange = [self textRangeFromPosition:selectedRange.end toPosition:selectedRange.end];

        //Set the new range
        [self setSelectedTextRange:newRange];

        return NO;
    } else {
        //Handle other actions?
    }

    return [super canPerformAction:action withSender:sender];
}

UITextFieldDelegate方法

//Select the text when text field receives focus
- (void) textFieldDidBeginEditing:(UITextField *)textField
{
    [textField selectAll:nil];
}

//Hide the keyboard when the keyboard "Done" button is pressed
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];

    return TRUE;
}

希望对您有所帮助！