UIMenuController的快速使用

前言
UIMenuController是一种UIKit中提供的一种使用比较简单的菜单控件。今天无意中看到这个控件，发现对其使用有些模糊了，故此把以前项目中对它的使用抽出来，做一个简单的总结,旨在指导快速上手。

须知

• 默认情况下只有UITextField、UITextView、UIWebView支持并内置UIMenuController的控件
• 要让其他控件也支持UIMenuController(比如UILabel、UIView等)，就必须自定义控件，并实现2个方法特定方法

控件使用效果如下

图1. 原生UITextField效果

图2. UILabel自定义样式

1. 如何让UITextField、UITextView、UIWebView显示UIMenuController的控件

    // 成为第一响应者
    [self.label becomeFirstResponder];
    
    UIMenuController *menuController = [UIMenuController sharedMenuController];
    // 设置UIMenuItem
    menuController.menuItems = menuItems;
    // 设置显示方向
    menuController.arrowDirection = UIMenuControllerArrowUp;
    // targetRect: MenuController需要指向的矩形框
    // targetView: targetRect会以targetView的左上角为坐标原点
    [menuController setTargetRect:self.label.bounds inView:self.label];
    // 显示
    [menuController setMenuVisible:YES animated:YES];

2.自定义可以使用UIMenuController的控件(以UILabel为例)

• 1. 自定义一个叫TLMenuLabel的Label（这步不是重点，可以直接跳过）

typedef void(^TLMenuItemDidClick)(NSString *title,UIMenuController *menu);

@interface TLMenuLabel : UILabel
// 对外API
/** 允许复制：默认YES */
@property (nonatomic,assign) BOOL allowCopy;
/** Ping：默认NO */
@property (nonatomic,assign) BOOL allowPing;
/** tracert：默认NO */
@property (nonatomic,assign) BOOL allowTracert;
/** tcping：默认NO */
@property (nonatomic,assign) BOOL allowTcping;
/** ipconfig：默认NO */
@property (nonatomic,assign) BOOL allowDig;
/** 生成报告：默认NO */
@property (nonatomic,assign) BOOL allowReport;

/** 自定义的MenuItem被点击回调 */
@property (nonatomic,copy) TLMenuItemDidClick itemDidClick;
@end

@implementation TLMenuLabel
// 初始化
- (void)awakeFromNib {
    [super awakeFromNib];
    [self setup];
}

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

- (void)setup {
    self.userInteractionEnabled = YES;
    _allowCopy = YES;
    _allowPing = YES;
    _allowTracert = NO;
    _allowTcping = YES;
    _allowDig = NO;
    _allowReport = YES;
    UILongPressGestureRecognizer *longPress
    = [[UILongPressGestureRecognizer alloc]
       initWithTarget:self
       action:@selector(onLongPress:)];
    [self addGestureRecognizer:longPress];
}
@end

• 2. 重写2个特定方法（重点）,重写后这个自定义label就支持UIMenuController控件了

// 1. 重写  `- canBecomeFirstResponder`
// ⚠️不能是` - (BOOL)becomeFirstResponder`
- (BOOL)canBecomeFirstResponder{
    return self.allowCopy || self.allowPing ||
           self.allowTracert || self.allowTcping ||
           self.allowDig || _allowReport;
}

// 2. 重写`- canPerformAction: withSender:`
/**
 * label能执行哪些操作(比如copy, paste等等)
 * @return  YES:支持这种操作
 */
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{

    // 根据你的需求 使能 你需要的操作，这个方法会根据你设置的menuItems多次调用

    if (action == @selector(copyText:)){
        return self.allowCopy;
    }
    if (action == @selector(ping:)){
        return self.allowPing;
    }
    if (action == @selector(tracert:)){
        return self.allowTracert;
    }
    if (action == @selector(tcping:)){
        return self.allowTcping;
    }
    if (action == @selector(dig:)){
        return self.allowDig;
    }
    if (action == @selector(report:)){
        return self.allowReport;
    }
    return NO; // 禁止系统操作类型（返回YES，系统操作类型也会显示）
}

• 3. 显示(此处通过长按手势唤醒)

- (void)onLongPress:(UILongPressGestureRecognizer *)longPress{
    switch (longPress.state) {
        case UIGestureRecognizerStateBegan:
        {
            _bgColor = self.backgroundColor;
            self.backgroundColor = [UIColor colorWithWhite:1 alpha:0.9];
            
            // 需要显示的额外条件
            if (self.text == nil || self.text.length < 1) return;
            if (![self canBecomeFirstResponder]) return;
        
            [self becomeFirstResponder];
            
            // 创建UIMenuItem
            NSArray *titles = @[@"Ping",@"Tracert",@"Tcping",@"Dig",@"生成报告",@"复制"];
            NSArray *actions = @[@"ping:",@"tracert:",@"tcping:",@"dig:",@"report:",@"copyText:"];
            self.items = [NSMutableArray array];
            for (NSString *title in titles) {
                NSUInteger index = [titles indexOfObject:title];
               //  ⚠️要确保这些Action都有实现（见下面第4步） 
                SEL sel = NSSelectorFromString(actions[index]);
                UIMenuItem *newItem = [[UIMenuItem alloc] initWithTitle:title action:sel];
                [self.items addObject:newItem];
            }
            
            // 获取UIMenuController单例
            UIMenuController *controller = [UIMenuController sharedMenuController];
            controller.menuItems = self.items;
            [controller setTargetRect:self.bounds inView:self];
            [controller setMenuVisible:YES animated:YES];
        }
            break;
        case UIGestureRecognizerStateEnded:
        case UIGestureRecognizerStateCancelled:
        case UIGestureRecognizerStateFailed:
            self.backgroundColor = _bgColor;
            break;
        default:
            break;
    }
    
}

• 4. UIMenuItem对应Action的实现(此步主要是提醒要实现Action)

- (void)ping:(UIMenuController *)menu
{
    if (self.itemDidClick) {
        self.itemDidClick(@"ping", menu);
    }
}

- (void)tracert:(UIMenuController *)menu
{
    if (self.itemDidClick) {
        self.itemDidClick(@"tracert -d", menu);
    }
}

- (void)tcping:(UIMenuController *)menu
{
    if (self.itemDidClick) {
        self.itemDidClick(@"tcping", menu);
    }
}


- (void)dig:(UIMenuController *)menu
{
    if (self.itemDidClick) {
        self.itemDidClick(@"dig", menu);
    }
}

- (void)report:(UIMenuController *)menu {
    if (self.itemDidClick) {
        self.itemDidClick(@"report", menu);
    }
}

- (void)copyText:(UIMenuController *)menu
{
    // 将自己的文字复制到粘贴板
    UIPasteboard *board = [UIPasteboard generalPasteboard];
    board.string = self.text;
    
//    if (self.itemDidClick) {
//        self.itemDidClick(@"copy", menu);
//    }
}