COMMAND + R 监听

#pragma mark 模拟器键盘事件
- (NSArray *)keyCommands
{
    
    static NSArray *keyCommands;
    
#if TARGET_IPHONE_SIMULATOR
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        UIKeyCommand *composeCommand = [UIKeyCommand keyCommandWithInput:@"r"
                                                           modifierFlags:UIKeyModifierCommand
                                                                  action:@selector(composeShortcut:)];
        keyCommands = @[composeCommand];
    });
#endif
    return keyCommands;
}


- (void)composeShortcut:(UIKeyCommand *)command
{
    [self reloadAction];
}