NSArray数组分组归类

[TOC]

数组基本用法

遍历数组

// for循环
NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil nil]; 
 int count = array.count; 
 for (int i = 0; i<count; i++) {  id obj = [array objectAtIndex:i];  } 

// for in 快速遍历
NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil nil];  
int i =0;  
for (id obj in array) {  NSLog(@"%i-%@", i, obj);  i++;  }  

// 代码块遍历
NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];
[array enumerateObjectsUsingBlock:  ^(id obj, NSUInteger idx, BOOLBOOL *stop) {  NSLog(@"%i-%@", idx, obj);  
    // 如果索引为1，就停止遍历  
    if (idx == 1) { 
       // 利用指针修改外面BOOL变量的值 
       *stop = YES; 
    } 
}]; 

数组排序

// 第一种
NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil nil]; 
// 返回一个排好序的数组，原来数组的元素顺序不会改变 
// 指定元素的比较方法：compare:
NSArray *array1 = [array sortedArrayUsingSelector:@selector(compare:)]; NSLog(@"array1:%@", array1);

// 第二种
NSArray *sortDesc = @[[[NSSortDescriptor alloc] initWithKey:nil ascending:YES]];
NSArray *sortSetArray = [array sortedArrayUsingDescriptors:sortDesc];

// 第三种
NSArray *test = @[ 1.8T,2.0T,2.0T,3.0L,1.8T,1.8T,2.0T,3.0L,1.8T,2.0T,1.8T,1.8T, 2.0T,1.8T,2.0T,2.0T,3.2L,1.8T,1.8T,2.0T,2.0T,3.2L,2.0T,3.2L, ];
NSArray *array3 = [self getNewArray test];
// 返回一个排序好的数组
- (NSArray *)getNewArray:(NSArray *)array {
      NSArray *arrayM = [array sortedArrayUsingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {
      if (NSOrderedDescending == [obj1 compare:obj2 options:NSNumericSearch]) {  
          return (NSComparisonResult)NSOrderedDescending;  
      } 
      if (NSOrderedAscending==[obj1 compare:obj2 options:NSNumericSearch]) {  
          return (NSComparisonResult)NSOrderedAscending;  
      } 
      return (NSComparisonResult)NSOrderedSame; 
  }]; 
      return arrayM;
}

分组归类

使用场景 ：根据NSAarry中NSDictionary的一个key值,将数组重新分组，下面是后台返回的数据：

(   
{brand_id = 1; brand_name = 奥迪; initial = A;},
{brand_id = 2; brand_name = 阿斯顿·马丁; initial = A;}, 
{brand_id = 11; brand_name = 保时捷; initial = B;}, 
{brand_id = 7; brand_name = 宝马; initial = B;}, 
{brand_id = 24; brand_name = 昌河; initial = C;},
{brand_id = 22; brand_name = 长城; initial = C;}
)

代码实现：

NSArray *testArray = @[  
@{@"brand_id": @"1", @"brand_name": @"奥迪", @"initial": @"A"}, 
@{@"brand_id": @"2", @"brand_name": @"阿斯顿·马丁", @"initial": @"A"}, 
@{@"brand_id": @"3", @"brand_name": @"保时捷", @"initial": @"B"}, 
@{@"brand_id": @"4", @"brand_name": @"宝马", @"initial": @"B"}, 
@{@"brand_id": @"4", @"brand_name": @"昌河", @"initial": @"C"}, 
@{@"brand_id": @"5", @"brand_name": @"长城", @"initial": @"C"} ];

// 获取数组中所用的initial的value值,indexArray数组中是乱序排列的。
NSMutableArray *indexArray = [NSMutableArray array]; 
indexArray = [testArray valueForKeyPath:@"initial"];
// 将array装换成NSSet类型，重新排序生成新的数组
NSSet *indexSet = [NSSet setWithArray:indexArray];
NSArray *sortDesc = @[[[NSSortDescriptor alloc] initWithKey:nil ascending:YES]];
NSArray *sortSetArray = [indexSet sortedArrayUsingDescriptors:sortDesc];
// 遍历数组并进行归类
NSMutableArray *resultArray = [NSMutableArray array];
[sortSetArray enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) { 
    // 根据NSPredicate获取array 
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"initial == %@",obj]; NSArray *indexArray = [testArray filteredArrayUsingPredicate:predicate];  
    // 将查询结果加入到resultArray中
    [resultArray addObject:indexArray]; 
}];

过滤重复元素和排序

// 最简洁，但返回的结果是无序的。
NSArray *arr = @[@"12-11", @"12-11", @"12-11", @"12-12", @"12-13", @"12-14"]; 
NSSet *set = [NSSet setWithArray:arr]; 

// 去除相同元素并重新排序
NSArray *arr = @[@"12-11", @"12-11", @"12-11", @"12-12", @"12-13", @"12-14"]; 
NSSet *set = [NSSet setWithArray:arr]; 
NSArray *sortDesc = @[[[NSSortDescriptor alloc] initWithKey:nil ascending:YES]]; 
NSArray *sortSetArray = [set sortedArrayUsingDescriptors:sortDesc];

// 利用NSDictionary的AllKeys（AllValues）方法
NSArray *dataArray =@[@"12-11", @"12-11", @"12-11", @"12-12", @"12-13", @"12-14"]; 
NSMutableDictionary *dic = [[NSMutableDictionary alloc]initWithCapacity:0]; 
for(NSString *str in dataArray){  
    [dic setValue:str forKey:str]; 
} 
NSLog(@"%@",[dic allKeys]);

// 利用数组的containsObject来去除
NSArray *dataArray =@[@"12-11", @"12-11", @"12-11", @"12-12", @"12-13", @"12-14"]; 
NSMutableArray *listAry = [[NSMutableArray alloc]init];  
for (NSString *str in dataArray) {  
    if (![listAry containsObject:str]) { 
         [listAry addObject:str];  
    }  
} 
NSLog(@"%@",listAry);