如何在數組中查找重複值？

Question

我的工作在SQLite和我寫了一個查詢返回了我兩個數組ItemsArray和CustomersIDArray爲：

ItemsArray 
Element at Index 0 = Off White, 
Element at Index 1 = Fan, 
Element at Index 2 = Off White, 
Element at Index 3 = Delux, 
Element at Index 4 = Fan 

CustomerIDArray 
Element at Index 0 = 1, 
Element at Index 1 = 2, 
Element at Index 2 = 2, 
Element at Index 3 = 3, 
Element at Index 4 = 4 

我想造成這樣的米白色= 2（算），範= 2（計數）和Delux = 1; 和合成陣列，

Result Array 
Element at Index 0 = Off White, 
Element at Index 1 = Fan, 
Element at Index 2 = Delux 

其實我想重複的第一陣列計數，但該值不能同爲CustomerArray。 請幫助我完成邏輯或代碼。

Answer 1

-(NSMutableArray *)getCountAndRemoveMultiples:(NSMutableArray *)array{ 

    NSMutableArray *newArray = [[NSMutableArray alloc]initWithArray:(NSArray *)array]; 
    NSMutableArray *countArray = [NSMutableArray new]; 
    int countInt = 1; 
    for (int i = 0; i < newArray.count; ++i) { 
     NSString *string = [newArray objectAtIndex:i]; 
     for (int j = i+1; j < newArray.count; ++j) { 
      if ([string isEqualToString:[newArray objectAtIndex:j]]) { 
       [newArray removeObjectAtIndex:j]; 
       countInt++; 
      } 
     } 
     [countArray addObject:[NSNumber numberWithInt:countInt]]; 
     countInt = 1; 
    } 
    NSMutableArray *finalArray = [[NSMutableArray alloc] initWithObjects:newArray, countArray, nil]; 
    NSLog(@"%@", finalArray); 
    return finalArray; 

} 
- (IBAction)getArrayInfo:(id)sender { 
    NSMutableArray *myArray = [[NSMutableArray alloc] initWithObjects:@"Off White", @"Fan", @"Off White", @"Deluxe", @"Fan", nil]; 
    NSMutableArray *godArray = [self getCountAndRemoveMultiples:myArray]; 
    NSLog(@"Array from this end = %@", godArray); 
} 

我剛剛成立-getArrayInfo對它進行測試。工作正常。正如你所看到的，你想要顯示的數組將在index：0處，而countArray在index處：1。

Answer 2

試試這個：

NSArray *copy = [ItemsArray copy]; 

NSInteger index = [copy count] - 1; 

for (id object in [copy reverseObjectEnumerator]) { 

    if ([ItemsArray indexOfObject:object inRange:NSMakeRange(0, index)] != NSNotFound) { 
     [ItemsArray removeObjectAtIndex:index]; 
    } 
    index--; 
} 

Answer 3

使用NSCountedSet像下面

NSMutableArray *ary_res = [[NSMutableArray alloc] init]; 
    NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:@"11",@"13",@"34",@"9",@"13",@"34",@"9",@"2",nil]; 
    NSCountedSet *set = [[NSCountedSet alloc] initWithArray:array]; 
    for(id name in set) 
    { 
     if([set countForObject:name]==2) 
      [ary_res addObject:name]; 
    } 
    // 
    NSLog(@"%@",ary_res);