(iPhone)如何处理UITextView上的触摸？

Question

我正在试着处理iPhone的UITextView上的触碰。我成功地处理了点击和其他触摸事件，例如，创建了UIImageViews的一个子类，并实现了显然不能与UITextView一起工作的touchesBegan method...however :(

UITextView有用户交互和多点触控功能，只是为了sure...no没有joy。有人想办法解决这个问题吗？

Answer 1

UITextView (UIScrollView的子类)包含了大量的事件处理。它处理复制和粘贴以及数据检测器。也就是说，这可能是一个bug，它不会传递未处理的事件。

有一个简单的解决方案:你可以子类化UITextView并在你自己的版本中嵌入你自己的touchesEnded (和其他事件处理消息)，你应该在每个触摸处理方法中调用[super touchesBegan:touches withEvent:event];。

#import "MyTextView.h"  //MyTextView:UITextView
@implementation MyTextView

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    NSLog(@"touchesBegan");
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
        [super touchesBegan:touches withEvent:event];
    NSLog(@"touchesMoved");
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    NSLog(@"****touchesEnded");
    [self.nextResponder touchesEnded: touches withEvent:event]; 
    NSLog(@"****touchesEnded");
    [super touchesEnded:touches withEvent:event];
    NSLog(@"****touchesEnded");
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{
[super touches... etc]; 
NSLog(@"touchesCancelled");
}

Answer 2

如果你想在UITextView上处理单击/双击/三次点击，你可以委托UIGestureRecongnizer并在你的文本视图上添加手势识别器。

以下是示例代码(在viewDidLoad中)：

UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap)];

//modify this number to recognizer number of tap
[singleTap setNumberOfTapsRequired:1];
[self.textView addGestureRecognizer:singleTap];
[singleTap release];

和

-(void)handleSingleTap{
   //handle tap in here 
   NSLog(@"Single tap on view");
}

希望这能有所帮助:D

Answer 3

更好的解决方案(不使用任何东西或使用任何私有API :D )

如下所述，向文本视图添加新的UITapGestureRecognizers不会有预期的结果，处理程序方法永远不会被调用。这是因为UITextView已经设置了一些点击手势识别器，我认为他们的代理不允许我的手势识别器正常工作，我相信更改他们的代理可能会导致更糟糕的结果。

幸运的是，UITextView已经设置了我想要的手势识别器，问题是它会根据视图的状态而变化(即:输入日语时的手势识别器集与输入英语时的手势识别器集不同，也不在编辑模式下)。我通过在UITextView的一个子类中覆盖它们来解决这个问题：

- (void)addGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
{
    [super addGestureRecognizer:gestureRecognizer];
    // Check the new gesture recognizer is the same kind as the one we want to implement
    // Note:
    // This works because `UITextTapRecognizer` is a subclass of `UITapGestureRecognizer`
    // and the text view has some `UITextTapRecognizer` added :)
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
        UITapGestureRecognizer *tgr = (UITapGestureRecognizer *)gestureRecognizer;
        if ([tgr numberOfTapsRequired] == 1 &&
            [tgr numberOfTouchesRequired] == 1) {
            // If found then add self to its targets/actions
            [tgr addTarget:self action:@selector(_handleOneFingerTap:)];
        }
    }
}
- (void)removeGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
{
    // Check the new gesture recognizer is the same kind as the one we want to implement
    // Read above note
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
        UITapGestureRecognizer *tgr = (UITapGestureRecognizer *)gestureRecognizer;
        if ([tgr numberOfTapsRequired] == 1 &&
            [tgr numberOfTouchesRequired] == 1) {
            // If found then remove self from its targets/actions
            [tgr removeTarget:self action:@selector(_handleOneFingerTap:)];
        }
    }
    [super removeGestureRecognizer:gestureRecognizer];
}

- (void)_handleOneFingerTap:(UITapGestureRecognizer *)tgr
{
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:tgr forKey:@"UITapGestureRecognizer"];
    [[NSNotificationCenter defaultCenter] postNotificationName:@"TextViewOneFingerTapNotification" object:self userInfo:userInfo];
    // Or I could have handled the action here directly ...
}

通过这样做，无论文本视图何时更改其手势识别器，我们都将始终捕获我们想要的点击手势识别器。因此，我们的→方法将被相应地调用:)

结论：如果你想在UITextView中添加一个手势识别器，你必须检查文本视图是否已经有了它。

• 如果没有，只需按常规方式操作即可。(创建您的手势识别器，设置它，并将其添加到文本视图中)，就完成了！.
• 如果它有它，那么您可能需要执行类似于上面的操作。

​

​

旧答案

我是通过使用私有方法的得到这个答案的，因为之前的答案有缺点，它们不能像预期的那样工作。在这里，我只是截取被调用的方法，然后调用原始方法，而不是修改UITextView的点击行为。

进一步解释

UITextView有一堆专门的UIGestureRecognizers，每个都有一个target和一个action，但是它们的target不是UITextView本身，它是forward类UITextInteractionAssistant的一个对象。(此助手是UITextView的@package ivar，但转发定义在公共标头中: UITextField.h)。

UITextTapRecognizer识别taps并调用UITextInteractionAssistant上的oneFingerTap:，因此我们希望拦截该调用:)

#import <objc/runtime.h>

// Prototype and declaration of method that is going be swizzled
// When called: self and sender are supposed to be UITextInteractionAssistant and UITextTapRecognizer objects respectively
void proxy_oneFingerTap(id self, SEL _cmd, id sender);
void proxy_oneFingerTap(id self, SEL _cmd, id sender){ 
    [[NSNotificationCenter defaultCenter] postNotificationName:@"TextViewOneFinderTap" object:self userInfo:nil];
    if ([self respondsToSelector:@selector(proxy_oneFingerTap:)]) {
        [self performSelector:@selector(proxy_oneFingerTap:) withObject:sender];
    }
}

...
// subclass of UITextView
// Add above method and swizzle it with.
- (void)doTrickForCatchingTaps
{
    Class class = [UITextInteractionAssistant class]; // or below line to avoid ugly warnings
    //Class class = NSClassFromString(@"UITextInteractionAssistant");
    SEL new_selector = @selector(proxy_oneFingerTap:);
    SEL orig_selector = @selector(oneFingerTap:);

    // Add method dynamically because UITextInteractionAssistant is a private class
    BOOL success = class_addMethod(class, new_selector, (IMP)proxy_oneFingerTap, "v@:@");
    if (success) {
        Method originalMethod = class_getInstanceMethod(class, orig_selector);
        Method newMethod = class_getInstanceMethod(class, new_selector);
        if ((originalMethod != nil) && (newMethod != nil)){
            method_exchangeImplementations(originalMethod, newMethod); // Method swizzle
        }
    }
}

//... And in the UIViewController, let's say

[textView doTrickForCatchingTaps];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewWasTapped:) name:@"TextViewOneFinderTap" object:nil];

- (void)textViewWasTapped:(NSNotification *)noti{
    NSLog(@"%@", NSStringFromSelector:@selector(_cmd));
}