使用UITextView的自动补全应该更改范围内的文本 [英] Autocompletion using UITextView should change text in range

问题描述

我在这里遵循了Ray Wenderlich的关于文本自动完成的教程： http://www.raywenderlich.com/336/how-to-auto-complete-with-custom-values

效果很好，但是它仅允许搜索textView中包含的字符串。我需要它在同一视图中搜索多个字符串。例如：

 您好@ user，@ steve 
   
 
 
应搜索两个出现的@。这是原始代码：
 -（BOOL）textField：（UITextField *）textField shouldChangeCharactersInRange：（NSRange）range 
 replacementString：（NSString *）string {
 autocompleteTableView.hidden = NO; 
 
 NSString * substring = [NSString stringWithString：textField.text]; 
 substring = [substring stringByReplacingCharactersInRange：range withString：string]; 
 [self searchAutocompleteEntriesWithSubstring：substring]; 
返回是； 
} 
  
这是我的：
 -（BOOL）textField：（UITextField *）textField shouldChangeCharactersInRange：（NSRange）range 
 replaceString：（NSString *）string {
 
 NSArray *项目= [textView.text componentsSeparatedByString：@ @]; 
 
 if（[项目计数]> 0&& [[[项目lastObject]长度]）{
 NSString * substring = [NSString stringWithString：[项目lastObject]]]; 
 [self searchAutocompleteEntriesWithSubstring：substring]; 
 
} 
返回是； 
} 
  
一切正常，但似乎是后面的角色。因此，键入 J将什么都不会产生，但是 Jo将返回 J的结果。我认为它与以下内容有关：
  [substring stringByReplacingCharactersInRange：range withString：string] 
  
但是我尝试使用NSRange超出范围时都会崩溃。
解决方案
首先，我们是在谈论文本字段还是文本视图？他们是不同的！您的代码同时引用了两者。我将只使用 textField ，因为那是方法的名称。
 
 
 
在您收到 textField：shouldChangeCharactersInRange：replacementString：， textField.text 尚未更改为包含替换字符串。因此，当用户键入 J时， textField.text 尚不包含 J 。
 
 
 
 Ray的方法通过执行替换来处理此问题。当您尝试进行替换时，它会失败，因为您的子字符串变量不包含 textField.text 的副本。您的子字符串仅包含 textField.text 的一部分。这就是为什么出现越界异常的原因-您的范围超出了范围，因为 substring 比 textField.text 。
 
 
 
所以也许您应该在分割字符串之前执行替换。试试这个：
 -（BOOL）textField：（UITextField *）textField shouldChangeCharactersInRange：（NSRange）range replaceString：（NSString *）字符串{
 NSString * changedText = [textField.text stringByReplacingCharactersInRange：range withString：string]; 
 NSArray *项目= [changedText componentsSeparatedByString：@ @]; 
 
 if（[项目计数]> 0&& [[[项目lastObject]长度]）{
 NSString * substring = [NSString stringWithString：[项目lastObject]]]; 
 [self searchAutocompleteEntriesWithSubstring：substring]; 
 
} 
返回是； 
 
} 
  
 
I followed Ray Wenderlich's tutorial on text autocompletion here: http://www.raywenderlich.com/336/how-to-auto-complete-with-custom-values

And it works great, but it only allows searching for a string that is contained in the textView. I need it to search for multiple strings in the same view. For example: 
Hi @user, how's @steve
Should search for both occurrences of the @. Here is the original code:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range 
replacementString:(NSString *)string {
 autocompleteTableView.hidden = NO;

    NSString *substring = [NSString stringWithString:textField.text];
    substring = [substring stringByReplacingCharactersInRange:range withString:string];
    [self searchAutocompleteEntriesWithSubstring:substring];
    return YES;
}
And here is mine:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range 
replacementString:(NSString *)string {

NSArray* items = [textView.text componentsSeparatedByString:@"@"];

if([items count] > 0 && [[items lastObject] length]){
    NSString *substring = [NSString stringWithString:[items lastObject]];
    [self searchAutocompleteEntriesWithSubstring:substring];

    }
return YES;
}
And everything works, but it seems to be a character behind. So typing "J" would result in nothing, but "Jo" would return results for "J". I'm thinking it has to do with:
 [substring stringByReplacingCharactersInRange:range withString:string]
But anything I try crashes with an NSRange out of bounds.
解决方案
First of all, are we talking about a text field or a text view?  They are different!  Your code refers to both.  I will just go with textField since that's in the name of the method.

At the time you receive textField:shouldChangeCharactersInRange:replacementString:, textField.text has not been changed to contain the replacement string.  So when the user types "J", textField.text doesn't contain the J yet.

Ray's method handles this by performing the substitution.  When you try to do the substitution, it fails because your substring variable doesn't contain a copy of textField.text.  Your substring only contains a part of textField.text.  That's why you get an out-of-bounds exception - your range is out of bounds because substring is shorter than textField.text.

So perhaps you should perform the replacement before you split the string. Try this:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSString *changedText = [textField.text stringByReplacingCharactersInRange:range withString:string];
    NSArray* items = [changedText componentsSeparatedByString:@"@"];

    if([items count] > 0 && [[items lastObject] length]){
        NSString *substring = [NSString stringWithString:[items lastObject]];
        [self searchAutocompleteEntriesWithSubstring:substring];

    }
    return YES;

}


                        
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