今天再把NSDictionary的一些方法归归类，做一个工具博客出来。

NSDictionary

一：NSDictionary的初始化

NSDictionary *dic = @{@"name":@"lilei",@"age":@"13"};
NSDictionary *dic1 = [NSDictionary new];
NSDictionary *dic2 = [[NSDictionary alloc]initWithDictionary:dic1];
NSDictionary *dic3 = [[NSDictionary alloc]initWithObjectsAndKeys:@"lilei",@"name",@"13",@"age", nil];
NSArray *keyArray = @[@"name",@"age"];
NSArray *valueArray = @[@"lilei",@"13"];
NSDictionary *dic4 = [[NSDictionary alloc]initWithObjects:valueArray forKeys:keyArray];

二：NSDictionary的属性

NSDictionary *dic = @{@"name":@"lilei",@"age":@"13"};
NSInteger count = dic.count; // 字典里键值对的个数
NSArray *allKeys = dic.allKeys; // 字典里的所有键
NSArray *allValues = dic.allValues; // 字典里的所有值
NSString *description = dic.description;  // 字典的描述字符串

三：NSDictionary的一些常用方法

1：返回字典内一个值对应的所有键

NSDictionary *dic = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
NSArray *array = [dic allKeysForObject:@"13"];

返回的array是 @[@"age",@"class"];

2：是否完全与另一个字典相同

NSDictionary *dic1 = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
NSDictionary *dic2 = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
BOOL isSame = [dic1 isEqualToDictionary:dic2];

返回YES

3：使用block来遍历字典的键值对

NSDictionary *dic1 = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
[dic1 enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
        // 遍历字典的所有键值对
}];
[dic1 enumerateKeysAndObjectsWithOptions:NSEnumerationReverse usingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
        // 倒序遍历字典的所有键值对
}];

4：让字典按照value的大小顺序来对keys键值进行排序

NSDictionary *dic1 = [NSDictionary dictionaryWithObjectsAndKeys:@"4",@"A",@"6",@"C",@"5",@"B",nil];
NSArray *array = [dic1 keysSortedByValueUsingSelector:@selector(compare:)];
NSLog(@"排序键值对%@",array);

array的值为 @[@"A",@"B",@"C"]; 跟NSArray一样，有Function【函数】，Comparator【比较】，Selector【选择器】几种方式来进行排序

NSMutableDictionary

1：讲一个字典中的所有属性新增到可变字典中

NSDictionary *dic1 = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
NSMutableDictionary *mDic = [NSMutableDictionary new];
[mDic addEntriesFromDictionary:dic1];

2：从可变字典中移除键值对

NSDictionary *dic1 = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
NSMutableDictionary *mDic = [[NSMutableDictionary alloc]initWithDictionary:dic1];
[mDic removeObjectForKey:@"name"]; // 移除name的键值对
[mDic removeAllObjects]; // 移除所有键值对

3：修改或新增可变数组的键值对【如果新增的键值对本来就有，则修改否则新增】

NSDictionary *dic1 = @{@"name":@"lilei",@"age":@"13",@"class":@"13"};
NSMutableDictionary *mDic = [[NSMutableDictionary alloc]initWithDictionary:dic1];
[mDic setObject:@"hanmeimei" forKey:@"name"]; // 更新了原有的name键值对
[mDic setObject:@"color" forKey:@"white"]; // 新增了值为white的color键值对