@interface StringPermutations : NSObject  
- (void)permuteString:(NSString *)inputString;  
@end  
#import "StringPermutations.h"  
@implementation StringPermutations  
- (void)permuteString:(NSString *)inputString {  
  NSString *chars = inputString;  
  NSArray *charArray = [chars componentsSeparatedByString: @""];  
  if (charArray.count <= 1) {  
    NSLog(@"排列结果：%@", inputString);  
    return;  
  }  
  NSMutableString *result = [NSMutableString string];  
  void permute(NSArray *array, NSUInteger index, NSString *currentString,  
             NSMutableArray *used, NSString *resultString) {  
    if (index == array.count) {  
      [resultString appendFormat: @"'%@'", currentString];  
      [result appendString: resultString];  
      [resultString reset];  
      return;  
    }  
    for (NSUInteger i = 0; i < array.count; i++) {  
      if (![(NSNumber *)[array objectAtIndex:i] boolValue]) {  
        [permute array: array, index: i+1, currentString: [currentString appendFormat: @"'%c'",  
                   [array[i] characterAtIndex: 0]], used: used, resultString: resultString);  
      }  
    }  
    [resultString reset];  
  }  
  NSMutableArray *used = [NSMutableArray array];  
  [permute charArray, 0, @"", used, result];  
  for (NSString *str in [result componentsSeparatedByString: @"\n"]) {  
    NSLog(@"排列结果：%@", str);  
  }  
}  
@end