將NSString的中間內容替換爲其他內容

Question

我有一個字符串，例如「a，b，c，d，e，f，g，h」，現在我想替換從索引4 &結尾開始的內容在索引6處。

因此在例子中，結果字符串將是「a，b，c，d，f，e，g，h」。

FYI唯一的全動態內容包括索引被替換..

我不知道如何做到這一點..任何幫助表示讚賞！

Answer 1

看起來從您要在字符串替換部件的例子（即指數4是第四分隔的字母 - 的「E」）。如果是這樣的話，那麼解決的辦法是用的NSString componentsSeparatedByString：和componentsJoinedByString：

// string is a comma-separated set of characters. replace the chars in string starting at index 
// with chars in the passed array 

- (NSString *)stringByReplacingDelimitedLettersInString:(NSString *)string withCharsInArray:(NSArray *)chars startingAtIndex:(NSInteger)index { 

    NSMutableArray *components = [[string componentsSeparatedByString:@","] mutableCopy]; 

    // make sure we start at a valid position 
    index = MIN(index, components.count-1); 

    for (int i=0; i<chars.count; i++) { 
     if (index+i < components.count) 
      [components replaceObjectAtIndex:index+i withObject:chars[i]]; 
     else 
      [components addObject:chars[i]]; 
    } 
    return [components componentsJoinedByString:@","]; 
} 

- (void)test { 
    NSString *start = @"a,b,c,d,e,f,g"; 
    NSArray *newChars = [NSArray arrayWithObjects:@"x", @"y", @"y", nil]; 
    NSString *finish = [self stringByReplacingDelimitedLettersInString:start withCharsInArray:newChars startingAtIndex:3]; 
    NSLog(@"%@", finish); // logs @"a,b,c,x,y,z,g" 

    finish = [self stringByReplacingDelimitedLettersInString:start withCharsInArray:newChars startingAtIndex:7]; 
    NSLog(@"%@", finish); // logs @"a,b,c,d,e,f,x,y,z" 
} 

Answer 2

在這種情況下，最好是NSMutableString。請看下面的例子：

int a = 6; // Assign your start index. 
int b = 9; // Assign your end index. 

NSMutableString *abcd = [NSMutableString stringWithString:@"abcdefghijklmano"]; // Init the NSMutableString with your string. 
[abcd deleteCharactersInRange:NSMakeRange(a, b)]; //Now remove the charachter in your range. 

[abcd insertString:@"new" atIndex:a]; //Insert your new string at your start index.