APP支持外接键盘

#pragma mark - key commmand 外接键盘
- (BOOL)canBecomeFirstResponder
{
    return YES;
}

- (NSArray<UIKeyCommand *> *)keyCommands
{
    NSString *space = [NSString stringWithFormat:@"%c", 32];//空格
    
    return @[[UIKeyCommand keyCommandWithInput:space modifierFlags:0 action:@selector(onClickKeyCommand:) discoverabilityTitle:ACLocalizedString(@"play_or_pause", @"播放/暂停")],[UIKeyCommand keyCommandWithInput:UIKeyInputLeftArrow modifierFlags:0 action:@selector(onClickKeyCommand:) discoverabilityTitle:ACLocalizedString(@"pre_frame", @"上一帧")],[UIKeyCommand keyCommandWithInput:UIKeyInputRightArrow modifierFlags:0 action:@selector(onClickKeyCommand:) discoverabilityTitle:ACLocalizedString(@"next_frame", @"下一帧")]];
}

- (void)onClickKeyCommand:(UIKeyCommand *)keyCommand
{
    NSString *space = [NSString stringWithFormat:@"%c", 32];
    
    if(keyCommand.modifierFlags == 0 && [keyCommand.input isEqualToString:space])
    {

    }
    
    if(keyCommand.modifierFlags == 0 && [keyCommand.input isEqualToString:UIKeyInputLeftArrow])
    {
        
    }
    
    if(keyCommand.modifierFlags == 0 && [keyCommand.input isEqualToString:UIKeyInputRightArrow])
    {
        
    }
}