字典NSDictionary和NSMutableDictionary的使用

简介：字典是一种数据结构，字典里面的每一个元素，是一个key-value（键值对），key和value都是对象类型。同NSArray一样，里面的对象不用保持一致性。

NSDictionary

1、字面量初始化

// 存储时时无序的

NSDictionary *dict = @{@"name" : @"xiaoming", @"gendar" : @"man", @"age" : @""};

// 打印时根据Unicode码排序打印

NSLog(@"%@", dict);

2、实例方法初始化

NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", nil];

3、类方法初始化

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", nil];

4、打印key-value的对数

 NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", nil];

 NSLog(@"%@", dict.count);

注意：key-value键值对中的key具有唯一性，value可以相同。也就是说，栗子如下：

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", @"woman", @"gendar", nil];

NSLog(@"%@", dict);

====打印

{

    age = ;

    gendar = man;

    name = xiaoming;

}

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", @"man", @"lastGendar", nil];

NSLog(@"%@", dict);

====打印

{

    age = ;

    gendar = man;

    lastGendar = man;

    name = xiaoming;

}

5、根据key取出相应的value

NSDictionary *dict = @{@"name" : @"xiaoming", @"gendar" : @"man", @"age" : @""};

// valueForKey是NSDictionary的分类中的一个方法

NSString *nameString = [dict valueForKey:@"name"];

// objectForKey是NSDictionary本身定义的一个方法

NSString *ageString = [dict objectForKey:@"age"];

// 根据下标符取出value

NSString *gendarString = dict[@"gendar"];


NSLog(@"~~~~~~~~~~%@~~~~~~~~~~%@~~~~~~~~~~%@", nameString, ageString, gendarString);

====打印

~~~~~~~~~~xiaoming~~~~~~~~~~~~~~~~~~~~man

6、取出字典中所有的key、所有的value

NSDictionary *dict = @{@"name" : @"xiaoming", @"gendar" : @"man", @"age" : @""};

NSArray *keyArray = [dict allKeys];

NSArray *valueArray = [dict allValues];

NSLog(@"\n%@\n%@", keyArray, valueArray);

====打印

(

    name,

    gendar,

    age

)

(

    xiaoming,

    man,

)

7、判断两个字典对象是否相同

NSDictionary *dict1 = @{@"name" : @"小明", @"gendar" : @"男", @"age" : @""};

NSDictionary *dict2 = @{@"name" : @"小红", @"gendar" : @"男", @"age" : @""};

BOOL bo = [dict1 isEqualToDictionary:dict2];

NSLog(@"%@", bo ? @"两者相同" : @"两者不相同");

====打印

两者不相同

NSMutableDictionary

1、构建方法初始化

NSMutableDictionary *mDict = [[NSMutableDictionary alloc] init];

2、类方法初始化

NSMutableDictionary *mDict = [NSMutableDictionary dictionary];

3、根据key值修改对应的value（找不到对应的key，就相当于添加这一对key-value）

NSMutableDictionary *mDict = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", @"woman",

@"gendar", nil];

[mDict setObject:@"" forKey:@"age"];

[mDict setObject:@"China" forKey:@"address"];

NSLog(@"%@", mDict);

====打印

{

    address = China;

    age = ;

    gendar = woman;

    name = xiaoming;

}

4、根据key删除key-value键值对

NSMutableDictionary *mDict = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", @"xiaoming", @"name", @"woman",

@"gendar", nil];

[mDict removeObjectForKey:@"name"];

NSLog(@"%@", mDict);

====打印

{

    age = ;

    gendar = woman;

}

5、使用一个字典重置可变字典

 NSMutableDictionary *dict1 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"man", @"gendar", nil];

 NSMutableDictionary *dict2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"", @"age", @"woman", @"gendar", nil];

 [dict2 setDictionary:dict1];

 NSLog(@"%@", dict2);

 ====打印

{

    age = ;

    gendar = man;

}

----暂时这么多

巴特西

字典NSDictionary和NSMutableDictionary的使用

NSDictionary

NSMutableDictionary

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