keyValue

参考文档1
参考文档2

问题由组去重开始，随即看到keyValue，觉得有用，以后可以再深入学习。

数组去重的几种方法

• 字典的AllKeys

NSArray *dataArray = @[@"wf,@"wf2",@"wf3",@"wf"];
NSMutableDictionary *dic = [NSMutableDictionary dictionary];  
for(NSString *str in dataArray){
  [dic setValue:str forKey:str];
}
NSLog(@"%@",[dic allKeys]);

• 集合的AllObjects

NSSet *set = [NSSet setWithArray:dataArray];
NSLog(@"%@",[set allObjects]);

• 数组的containsObject 方法

NSMutableArray *listArr = [NSMutableArray array];
for(NSString *str in dataArray){
   if(![listArr containsObject:str]){
        [listArr addobject:str];
    }
}

• keyValue的方法

dataArray = [dataArray valueForKeyPath:@"distinctUnionOfObjects.self"];

valueForKeyPath

使用示例

 //数组内字符串写
NSArray *array = @[@"name", @"w", @"aa", @"jimsa"];
NSLog(@"%@", [array valueForKeyPath:@"uppercaseString"]);

//数组内字符长度
[array valueForKeyPath:@"length"];

或

 NSArray *array = @[@1, @2, @3, @4, @10];
 NSNumber *sum = [array valueForKeyPath:@"@sum.self"];
 NSNumber *avg = [array valueForKeyPath:@"@avg.self"];
 NSNumber *max = [array valueForKeyPath:@"@max.self"];
 NSNumber *min = [array valueForKeyPath:@"@min.self"];

或

//得到字典中每一个key 对应的value
NSArray *array = @[@{@"name" : @"cook",@"code" : @1},
                    @{@"name": @"jim",@"code" : @2},
                    @{@"name": @"jim",@"code" : @1},
                    @{@"name": @"jbos",@"code" : @1}];
NSLog(@"%@", [array valueForKeyPath:@"name"]);

//也可以直接去重
[array valueForKeyPath:@"@distinctUnionOfObjects.name"]；