iOS：按字母顺序重新排序NSString字符

Question

Objective-C中是否有一种方法可以按字母顺序重新排序字符串的字符？

例如：

  

输入：＆＃34; fhwoijc＆＃34;

     

输出：＆＃34; cfhijow＆＃34;

这就是我想出来的 - 虽然它已经做了很多工作

// Convert NSString to NSArray
NSMutableArray *letterArray = [NSMutableArray array];
NSString *letters = @"fhwoijc";
[letters enumerateSubstringsInRange:NSMakeRange(0, [letters length]) 
                            options:(NSStringEnumerationByComposedCharacterSequences) 
                         usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
    [letterArray addObject:substring];
}];

// Sort Array of strings alphabetically
[letterArray sortUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

// Convert Array back to NSString
NSString * result = [letterArray componentsJoinedByString:@""];