objective-c - 更新从文本字段绑定(bind)的属性，无需按 Enter 键

Question

我有一个文本字段，并将其绑定(bind)到一个 NSString 实例变量。

当我在文本字段中键入内容时，它不会更新变量。它会等到我按下 Enter 键。我不想每次都按 Enter 键。

我需要更改什么才能立即更改绑定(bind)值？

Answer 1

默认情况下，NSTextField 的值绑定(bind)不会持续更新。要解决此问题，您需要在选择文本字段后，选中“值”标题下的“绑定(bind)检查器”中的“连续更新值”框:

---

但是，大​​多数情况下，您真正​​想要做的是当用户完成编辑并按下按钮(“保存”或“确定”)时更新文本字段绑定(bind)的属性， 例如)。为此，您无需如上所述不断更新属性，只需结束编辑即可。 Daniel Jalkut provides an extremely useful implementation of just such a method :

@interface NSWindow (Editing)

- (void)endEditing;

@end

@implementation NSWindow (Editing)

- (void)endEditing
{
    // Save the current first responder, respecting the fact
    // that it might conceptually be the delegate of the 
    // field editor that is "first responder."
    id oldFirstResponder = [oMainDocumentWindow firstResponder];
    if ((oldFirstResponder != nil) &&
        [oldFirstResponder isKindOfClass:[NSTextView class]] &&
        [(NSTextView*)oldFirstResponder isFieldEditor])
    {   
        // A field editor's delegate is the view we're editing
        oldFirstResponder = [oldFirstResponder delegate];
        if ([oldFirstResponder isKindOfClass:[NSResponder class]] == NO)
        {
            // Eh ... we'd better back off if 
            // this thing isn't a responder at all
            oldFirstResponder = nil;
        }
    } 

    // Gracefully end all editing in our window (from Erik Buck).
    // This will cause the user's changes to be committed.
    if([oMainDocumentWindow makeFirstResponder:oMainDocumentWindow])
    {
        // All editing is now ended and delegate messages sent etc.
    }
    else
    {
        // For some reason the text object being edited will
        // not resign first responder status so force an 
        /// end to editing anyway
        [oMainDocumentWindow endEditingFor:nil];
    }

    // If we had a first responder before, restore it
    if (oldFirstResponder != nil)
    {
        [oMainDocumentWindow makeFirstResponder:oldFirstResponder];
    }
}

@end

因此，如果您有一个针对 View Controller 的方法 -save: 的“保存”按钮，您将调用

- (IBAction)save:(id)sender
{
    [[[self view] window] endEditing];
    //at this point, all properties bound to text fields have the same
    //value as the contents of the text fields.

    //save stuff...
}