如何处理在Cocoa应用程序中的箭头键事件？ [英] How to handle arrow key event in Cocoa app?

问题描述

（解决方案注释）

如何处理Cocoa应用程序中的箭头键事件？

How to handle arrow key event in Cocoa app?

推荐答案

查看此代码。我假设该类是 NSView 的子类。

See this code. I assumed the class is subclass of NSView.

#pragma mark    -   NSResponder

- (void)keyDown:(NSEvent *)theEvent
{
    NSString*   const   character   =   [theEvent charactersIgnoringModifiers];
    unichar     const   code        =   [character characterAtIndex:0];

    switch (code) 
    {
        case NSUpArrowFunctionKey:
        {
            break;
        }
        case NSDownArrowFunctionKey:
        {
            break;
        }
        case NSLeftArrowFunctionKey:
        {
            [self navigateToPreviousImage];
            break;
        }
        case NSRightArrowFunctionKey:
        {
            [self navigateToNextImage];
            break;
        }
    }
}

视图应为第一响应者接收事件。也许这个代码将需要支持。

A view should be first responder to receive events. Maybe this code will be required to support that.

#pragma mark    -   NSResponder
- (BOOL)canBecomeKeyView
{
    return  YES;
}
- (BOOL)acceptsFirstResponder
{
    return  YES;
}

要使用此方法，类应该是 NSResponder 。请参阅其他答案处理，而不对NSResponder进行子类化。

To use this method, the class should be subclass of NSResponder. See the other answer handling without subclassing NSResponder.

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