- (void)cut:(nullable id)sender NS_AVAILABLE_IOS(3_0);
- (void)copy:(nullable id)sender NS_AVAILABLE_IOS(3_0);
- (void)paste:(nullable id)sender NS_AVAILABLE_IOS(3_0);
- (void)select:(nullable id)sender NS_AVAILABLE_IOS(3_0);
- (void)selectAll:(nullable id)sender NS_AVAILABLE_IOS(3_0);
- (void)delete:(nullable id)sender NS_AVAILABLE_IOS(3_2);

// 比如我在一个 UITextView 里，想增加全选和复制的方法
// 只要在自定义 UITextView 的时候加入这行代码即可
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
 if(action == @selector(selectAll:) || action == @selector(copy:)) return YES;
 return NO;
}

- (BOOL)canBecomeFirstResponder {
 return YES;
}

- (void)setUp {
 /* 你可以在这里添加一些代码，比如字体、居中、夜间模式等 */
 self.userInteractionEnabled = YES;
 [self addGestureRecognizer:[[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPress)]];
}

- (void)longPress {
 
 // 设置label为第一响应者
 [self becomeFirstResponder];
 
 // 自定义 UIMenuController
 UIMenuController * menu = [UIMenuController sharedMenuController];
 UIMenuItem * item1 = [[UIMenuItem alloc]initWithTitle:@"复制" action:@selector(copyText:)];
 menu.menuItems = @[item1];
 [menu setTargetRect:self.bounds inView:self];
 [menu setMenuVisible:YES animated:YES];
}

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
 if(action == @selector(copyText:)) return YES;
 return NO;
}

// 如果模仿上面的写以下代码，点击后会导致程序崩溃
if(action == @selector(selectAll:) || action == @selector(copy:)) return YES; 

- (void)copyText:(UIMenuController *)menu {
 // 没有文字时结束方法
 if (!self.text) return;
 // 复制文字到剪切板
 UIPasteboard * paste = [UIPasteboard generalPasteboard];
 paste.string = self.text;
 
}