Question

我正在尝试对存储在两个不同数组中的两个字符串进行字符串比较。 90％的时间它工作，但另外10％的时间没有。在这种情况下，我正在比较城镇名称。

以下是我的代码：

//setup of string comparison
 NSString* string1 = [information from array 1];
 NSString *string2 = [information from array 2];

//remove whitespace.
  NSArray* string1sep = [string1 componentsSeparatedByCharactersInSet :[NSCharacterSet whitespaceCharacterSet]];
  NSString* string1rw = [string1sep componentsJoinedByString:@""];
  string1rw = [string1rw lowercaseString];

  NSArray* string2sep = [string2 componentsSeparatedByCharactersInSet :[NSCharacterSet whitespaceCharacterSet]];
  NSString* string2rw = [string2sep componentsJoinedByString:@""];
  string2rw = [string2rw lowercaseString];

//compare strings
  NSLog(@"%@ (%u): %@ (%u)", string1rw, [string1rw length], string2rw, [string2rw length]);
   if([string1rw isEqualToString:string2rw]){
                NSLog(@"Success");
        }

我的代码包含在for循环中，用于检查数组的每个元素。输出看起来像这样

                 -----------------------
                 Identifier 1
                 whangarei (9): whangarei (9)
                 whangarei (9): kaitaia (7)
                 whangarei (9): kerikeri (8)
                 whangarei (9): paruabay (8)
                 whangarei (9): kamo (4)
                 whangarei (9): tutukaka (8)
                 whangarei (9): auckland (8)
                 whangarei (9): kaiparacoast (12)
                 whangarei (9): paihia (6)
                 whangarei (9): hikurangi (9)
                 whangarei (9): hokianga (8)
                 whangarei (9): tba (3)
                 failure
                 -----------------------
                 Identifier 2
                 kaiparacoast (12): whangarei (9)
                 kaiparacoast (12): kaitaia (7)
                 kaiparacoast (12): kerikeri (8)
                 kaiparacoast (12): paruabay (8)
                 kaiparacoast (12): kamo (4)
                 kaiparacoast (12): tutukaka (8)
                 kaiparacoast (12): auckland (8)
                 kaiparacoast (12): kaiparacoast (12)
                 Success

字符串长度相同，拼写相同，均为去大写，两者都删除了空格。为什么这个用一个字符串而不是另一个？

对于人们的参考，这是我原来未清理的代码（有点难以阅读）

 - (BOOL) addToFilteredResults: (int) ofset{
     int catCount = 0;
     int citCount = 0;
     NSLog(@"-----------------------");
     NSLog(@"%@", [[CHARTeventsFull objectAtIndex:ofset]objectForKey:@"event"]);
     for(NSString *cityCheck in eventCities){
        if([[citySelected objectAtIndex:citCount] isEqual:[NSNumber numberWithBool:YES]]){

            //setup of string comparison
            NSArray* cityChecksep = [cityCheck componentsSeparatedByCharactersInSet :[NSCharacterSet whitespaceCharacterSet]];
            NSString* cityCheckrw = [cityChecksep componentsJoinedByString:@""];
            cityCheckrw = [cityCheckrw lowercaseString];

            NSString *city = [[CHARTeventsFull objectAtIndex:ofset]objectForKey:@"town"];
            NSArray* citysep = [city componentsSeparatedByCharactersInSet :[NSCharacterSet whitespaceCharacterSet]];
            NSString* cityrw = [citysep componentsJoinedByString:@""];
            cityrw = [cityrw lowercaseString];


            //comparison
            NSLog(@"%@ (%u): %@ (%u)", cityrw, [cityrw length], cityCheckrw, [cityCheckrw length]);
            if([cityCheckrw isEqualToString:cityrw]){


                 //doing another comparison here this code can be ignored for this question
                 //----------------------------
                 for(NSString *categoryCheck in eventCatagories){
                       if([[catagorySelected objectAtIndex:catCount] isEqual:[NSNumber numberWithBool:YES]]){
                            NSArray *categoriesFromEvent = [[CHARTeventsFull objectAtIndex:ofset]objectForKey:@"categories"];
                            for (NSString *category in categoriesFromEvent) {
                                 NSLog(@"%@ : %@", category, categoryCheck);
                                 if([categoryCheck isEqualToString:category]){
                                     NSLog(@"Success");
                                     return YES;
                                }
                             }
                         }
                   catCount++;
                   }
                   //---------------------------


              }
        }
        citCount++;
    }
    NSLog(@"failure");
    return NO;
}

Answer 1

你检查cityCheckrw是否等于cityrw，但你不打印“成功”，除非它通过你的第二次检查（你说我们可以忽略的那个）。问题似乎更有可能是在第二次检查或第二次for循环中，而不是两个相同的字符串没有评估为相等。当您将NSLog移动到cityCheckrw / cityrw检查下时，它是否仍然不会打印“成功”？

Answer 2

我已经解决了这个问题。我已经放弃使用'isEqualToString'并且现在使用谓词。不知道为什么'isEqualToString'在100％的时间内都不起作用，但在谓词中使用了基本相同的结构，并且它工作得很好。这是我对那些有相同问题的谓词所做的清理版本

1层解决方案

这有

arrayOfObjects              which never changes
filteredArrayOfObjects      which changes when filtered
filterArray1                which has the filters stored in it
filterArray1Selected        which has a BOOL indicating if the filter is active

和代码

//remove all objects from the filter array
[filteredArrayOfObjects removeAllObjects];

//set up compounder
NSMutableArray *compounder = [[NSMutableArray alloc] init];
int count = 0;

//go though the filter array and compound all the filters that are active
for(NSString *Check in FilterArray1){
    if([[filterArray1Selected objectAtIndex:count] isEqual:[NSNumber numberWithBool:YES]]){
        [compounder addObject:[NSPredicate predicateWithFormat:@"(filterName == %@)", Check]];
    }
    count++;
}

//compound the filters
NSPredicate *compounded = [NSCompoundPredicate orPredicateWithSubpredicates:compounder];

//filter the array
NSMutableArray *filteredArrayOfObjects = [[NSMutableArray alloc] initWithArray: [ArrayOfObjects filteredArrayUsingPredicate:compounded]];

也有2层解决方案，但它变得混乱

isEqualToString无法正确比较

2 个答案: