iOS拖拽控件到UITextView进行复制粘贴奔溃

前言

在iOS 15以后，我们可以通过拖拽一个控件（UITextField或UITextView）的形式将其内容复制粘贴到另一个UITextView，在拖拽之前，如果UITextView的内容为空，例如：@""、@" "（含空格），在设置代理- (void)textViewDidChange:(UITextView *)textView时，并且在代理中改变UITextView的内容后，或者 - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text返回NO如果不做特殊处理的话，一定会发生奔溃！

主要奔溃信息是：NSInternalInconsistencyException: Invalid parameter not satisfying: pos。

奔溃详情如下

CrashDoctor Diagnosis: Application threw exception NSInternalInconsistencyException: Invalid parameter not satisfying: pos
Thread 0 Crashed:
0   CoreFoundation                      0x00000001a8909d78 __exceptionPreprocess
1   libobjc.A.dylib                     0x00000001c156e734 objc_exception_throw
2   Foundation                          0x00000001aa18f1f0 _userInfoForFileAndLine
3   UIKitCore                           0x00000001abe850d4 -[_UITextKitTextPosition compare:]
4   UIKitCore                           0x00000001aad027d0 -[UITextInputController comparePosition:toPosition:]
5   UIKitCore                           0x00000001abe90a9c -[UITextView comparePosition:toPosition:]
6   UIKitCore                           0x00000001abe58dec -[UITextPasteController _clampRange:]
7   UIKitCore                           0x00000001abe595d8 __87-[UITextPasteController _performPasteOfAttributedString:toRange:forSession:completion:]_block_invoke
8   UIKitCore                           0x00000001abe597f0 __87-[UITextPasteController _performPasteOfAttributedString:toRange:forSession:completion:]_block_invoke.177
9   UIKitCore                           0x00000001abe81204 -[UITextInputController _pasteAttributedString:toRange:completion:]
10  UIKitCore                           0x00000001abe59524 -[UITextPasteController _performPasteOfAttributedString:toRange:forSession:completion:]
11  UIKitCore                           0x00000001abe587c4 __49-[UITextPasteController _executePasteForSession:]_block_invoke
12  libdispatch.dylib                   0x00000001a856ee68 _dispatch_call_block_and_release
13  libdispatch.dylib                   0x00000001a8570a2c _dispatch_client_callout
14  libdispatch.dylib                   0x00000001a857ef48 _dispatch_main_queue_drain
15  libdispatch.dylib                   0x00000001a857eb98 _dispatch_main_queue_callback_4CF
....................................................................

虽然这种情况很特殊，很少有用户去这样复制粘贴内容，但是一旦用户量大的话，或者用户总是使用这种方式去复制粘贴的话，奔溃的影响还是很大的。

例如，我们将第一个UITextView拖拽并复制内容Hello world到另一个UITextView，即发生奔溃，奔溃演示动画: 动画演示链接。

环境

Xcode 13.2.1
iPhone 13 Pro Max（模拟器）
iOS 15.2
M1 macOS Monterey 12.2.1

代码重现

新建一个工程，代码如下

@interface ViewController ()<UITextViewDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = UIColor.whiteColor;
    
    UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(50, 100, 120, 50)];
    textView.text = @"Hello world";
    textView.backgroundColor = UIColor.greenColor;
    textView.font = [UIFont systemFontOfSize:19];
    [self.view addSubview:textView];
    
    UITextView *textView1 = [[UITextView alloc] initWithFrame:CGRectMake(50, 180, 250, 200)];
    textView1.delegate = self;
    textView1.backgroundColor = UIColor.cyanColor;
    [self.view addSubview:textView1];
}

// MARK: - UITextViewDelegate

- (void)textViewDidChange:(UITextView *)textView {
    textView.text = @"Hello";
}

@end

在上面的代码中，我们拖拽textView并复制其内容Hello world到textView1，并在- (void)textViewDidChange:(UITextView *)textView中设置textView.text = @"Hello";，即改变textView1的内容。然后，运行项目，拖拽textView到textView1，即发生奔溃。

解决

目前，可以有2种方案解决。

方案一（推荐）

对要复制到的UITextView即textView1设置代理UITextPasteDelegate，如下

@interface ViewController ()<UITextViewDelegate, UITextPasteDelegate>

@end
 
textView1.pasteDelegate = self;

实现代理方法

// MARK: - UITextPasteDelegate

// Fix a crash where app will crash on iOS 15 or later if the user drags the UITextField or UITextView control to copy and paste.
- (UITextRange *)textPasteConfigurationSupporting:(id<UITextPasteConfigurationSupporting>)textPasteConfigurationSupporting
                   performPasteOfAttributedString:(NSAttributedString *)attributedString
                                          toRange:(UITextRange *)textRange {
    if ([textPasteConfigurationSupporting isKindOfClass:[UITextView class]]) {
        [(UITextView *)textPasteConfigurationSupporting replaceRange:textRange withText:attributedString.string];
    }
    return textRange;
}

在这个复制粘贴代理方法中，我们通过在复制粘贴的时候，对UITextView要复制粘贴的内容进行替换，就可以解决奔溃的问题。

方案二（不推荐）

和方案一唯一不同的是代理方法中的处理方式

- (UITextRange *)textPasteConfigurationSupporting:(id<UITextPasteConfigurationSupporting>)textPasteConfigurationSupporting
                   performPasteOfAttributedString:(NSAttributedString *)attributedString
                                          toRange:(UITextRange *)textRange {
    if ([textPasteConfigurationSupporting isKindOfClass:[UITextView class]] && UIPasteboard.generalPasteboard.hasStrings) { 
        [(UITextView *)textPasteConfigurationSupporting insertText:UIPasteboard.generalPasteboard.string ?: @""];
    }
    return textRange;
}

不推荐方案二的原因是，虽然避免了奔溃，我们无法获取到被拖拽的控件textView中的内容，也就是即使我们拖拽textView到textView1，textView1的内容依旧不会变化。但是要特别注意，有一种情况会变化，如果我们在手机中的任何地方已经复制了文本，然后通过拖拽textView到textView1，textView1会获取到已经复制的文本！例如，我们已经在短信中复制了“好的”，然后在应用中拖拽textView到textView1，如果textView的内容为空，textView1的内容就会变成“好的”，如果不为空，例如textView的内容为明白，，那么textView1的内容就会变成“明白，好的”。也就是说，通过方案二，拖拽控件永远只是执行粘贴操作。

注意：方案二需要用真机进行测试。

完整代码

@interface ViewController ()<UITextViewDelegate, UITextPasteDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = UIColor.whiteColor;
    
    UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(50, 100, 120, 50)];
    textView.text = @"Hello world";
    textView.backgroundColor = UIColor.greenColor;
    textView.font = [UIFont systemFontOfSize:19];
    [self.view addSubview:textView];
    
    UITextView *textView1 = [[UITextView alloc] initWithFrame:CGRectMake(50, 180, 250, 200)];
    textView1.delegate = self; 
    textView1.pasteDelegate = self;
    textView1.backgroundColor = UIColor.cyanColor;
    [self.view addSubview:textView1];
}

// MARK: - UITextViewDelegate

- (void)textViewDidChange:(UITextView *)textView {
    if (textView.text.length > 2) {
        textView.text = [textView.text substringFromIndex:2];
    } else {
        textView.text = @"";
    }
}

// MARK: - UITextPasteDelegate

//// Fix a crash where app will crash on iOS 15 or later if the user drags the UITextField or UITextView control to copy and paste.
- (UITextRange *)textPasteConfigurationSupporting:(id<UITextPasteConfigurationSupporting>)textPasteConfigurationSupporting
                   performPasteOfAttributedString:(NSAttributedString *)attributedString
                                          toRange:(UITextRange *)textRange {
    if ([textPasteConfigurationSupporting isKindOfClass:[UITextView class]]) {
        [(UITextView *)textPasteConfigurationSupporting replaceRange:textRange withText:attributedString.string];
    }
    return textRange;
}

/**
- (UITextRange *)textPasteConfigurationSupporting:(id<UITextPasteConfigurationSupporting>)textPasteConfigurationSupporting
                   performPasteOfAttributedString:(NSAttributedString *)attributedString
                                          toRange:(UITextRange *)textRange {
    if ([textPasteConfigurationSupporting isKindOfClass:[UITextView class]] && UIPasteboard.generalPasteboard.hasStrings) {
        [(UITextView *)textPasteConfigurationSupporting insertText:UIPasteboard.generalPasteboard.string ?: @""];
    }
    return textRange;
}
*/

@end

小结

拖拽前，如果要复制的UITextView（这里textView1）内容不为空（含空格），如"a"、"123"，无论是在- (void)textViewDidChange:(UITextView *)textView中改变内容或者- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text返回NO，一定不会奔溃。
拖拽前，如果要复制的UITextView（这里textView1）内容为空（如""、" "），无论是在- (void)textViewDidChange:(UITextView *)textView中改变内容或者- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text返回NO，一定会奔溃。
方案一和方案二都可以解决奔溃的问题，推荐方案一。

iOS拖拽控件到UITextView进行复制粘贴奔溃