iOS UILabel 實現長按選單複製功能：自訂類別與 UIMenuController 整合

核心步驟

1. 建立 UILabel 子類別（如 CopyableLabel）。
2. 啟用使用者互動：self.userInteractionEnabled = YES;。
3. 加入長按手勢辨識器：UILongPressGestureRecognizer。
4. 實作 canBecomeFirstResponder 回傳 YES。
5. 實作 canPerformAction:withSender: 僅回傳 copy: 為 YES。
6. 實作 copy: 將 self.text 寫入 [UIPasteboard generalPasteboard]。
7. 長按處理：[self becomeFirstResponder]，顯示 UIMenuController。

完整實作 (CopyableLabel.m)

@implementation CopyableLabel

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) [self setup];
    return self;
}
- (void)awakeFromNib { [super awakeFromNib]; [self setup]; }

- (void)setup {
    self.userInteractionEnabled = YES;
    UILongPressGestureRecognizer *lpgr = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
    [self addGestureRecognizer:lpgr];
}

- (BOOL)canBecomeFirstResponder { return YES; }

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    return action == @selector(copy:);
}

- (void)copy:(id)sender {
    [[UIPasteboard generalPasteboard] setString:self.text];
}

- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
    if (gesture.state == UIGestureRecognizerStateBegan) {
        [self becomeFirstResponder];
        UIMenuController *menu = [UIMenuController sharedMenuController];
        [menu setTargetRect:self.bounds inView:self];
        [menu setMenuVisible:YES animated:YES];
    }
}

@end

使用方式

// Storyboard/XIB 中將 Label 類別設為 CopyableLabel
// 或程式碼建立
CopyableLabel *label = [[CopyableLabel alloc] initWithFrame:CGRectMake(20, 100, 280, 40)];
label.text = @"長按我可以複製";
[self.view addSubview:label];

延伸：支援選取、全選

需實作 UITextInput 協定或改用 UITextView（editable=NO, selectable=YES）以獲得完整選取體驗。