目标c -如何找出一个keyCode是否对应于一个实际字符或功能键

Question

下面是我的代码。但是我怎么知道这个字符是否来自字母表呢?(任何字母，不只是a-z)

- (void)keyDown:(NSEvent *)theEvent
{
    NSString * const character = [theEvent charactersIgnoringModifiers];
}

Answer 1

您可以使用NSCharacterSet:

- (void)keyDown:(NSEvent *)theEvent
{
    NSString * const character = [theEvent charactersIgnoringModifiers];
    if ([character length] > 0)
    {
        unichar c = [character characterAtIndex:0];
        NSCharacterSet *letters = [NSCharacterSet letterCharacterSet];
        if ([letters characterIsMember:c])
        {
            NSLog(@"that's a letter!");
        }
    }
}

如果你经常调用这段代码，可能需要将letters存储为实例变量