iOS 数组归类分组 数组以年分组

arrayGrouping.m

/// 待分组数据 以年为单位分组
NSMutableArray *data = [NSMutableArray array];
for (int i = 2018; i > 2010; i--) {
    NSString *typeValue = [NSString stringWithFormat:@"%d年",i];
    for (int j = 1; j < 5; j++) {

        NSString *other = [NSString stringWithFormat:@"月份: %d月",j+(arc4random() % 5)];
        [data addObject:@{@"year":typeValue,@"month":other}];
    }
}
[data addObject:@{@"year":@"2019年",@"month":@"月份 1月"}];
NSArray *array = [data copy];

/// year属性数组
NSArray *tmpArr = [array valueForKeyPath:@"year"];

/// 有序set year去重
NSOrderedSet *set = [[NSOrderedSet alloc] initWithArray:tmpArr];

NSArray *sectionArr = [set array];

/// 分组 结果数组
NSMutableArray *groupArr = [NSMutableArray array];

/// 遍历去重后的year数组
[sectionArr enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    /// 以year过滤原数组
    NSPredicate *pre = [NSPredicate predicateWithFormat:@"year == %@",obj];
    NSArray *indexArr = [array filteredArrayUsingPredicate:pre];

    [groupArr addObject:indexArr];
}];
NSLog(@"分组后: %@",groupArr);
NSLog(@"分组前: %@",array);