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[操作系统]OC基本框架之


分类:NSDictionary(不可变数据字典)和NSMutableDictionary(可变数据字典)

组成:

(1)由键-值(Key-Value)对组成的数据集合
—(2)任何对象(id类型)都可以作键,但一般是字符串
—(3)字典内元素无序排列,键相同的的元素不能重复
—(4)可以通过键来快速枚举 
一、不可变数据字典
(1)字典的创建和初始化
 1  //1、用一个或多个键值对初始化一个字典对象: 以值,建,值,键,...,nil的顺序 2   NSDictionary *dict01=[[NSDictionary alloc] initWithObjectsAndKeys:@"key0",@"value0",@"key1",@"value1",@"key2",@"value2", nil]; 3   NSLog(@"dict01:%@",dict01); 4   NSDictionary *dict1=[NSDictionary dictionaryWithObjectsAndKeys:@123,@"key0",@456,@"key1",@678,@"key2", nil]; 5   NSLog(@"dict1:%@",dict1); 6   //2、用两个数组初始化一个字典,一个key数组,一个value数组,两个数组大小必须相等,否则Crash 7   NSArray *keyArray=@[@"name0",@"name1",@"name2"]; 8   NSArray *valueArray=@[@"hong",@"wang",@"zhao"]; 9   NSDictionary *dict02=[[NSDictionary alloc] initWithObjects:keyArray forKeys:valueArray];10   NSDictionary *dict2=[NSDictionary dictionaryWithObjects:valueArray forKeys:keyArray];11   NSLog(@"dict02:%@",dict02);12   NSLog(@"dict2:%@",dict2);13   14   //3、用一个数据字典初始化另一个数据字典15   NSDictionary *dict03=[[NSDictionary alloc] initWithDictionary:dict1];16   NSDictionary *dict3=[NSDictionary dictionaryWithDictionary:dict1];17   NSLog(@"dict03:%@",dict03);18   NSLog(@"dict3:%@",dict3);

 


(2)字典对象的创建和保存-文件

  //1、保存字典对象内容到文件  [dict3 writeToFile:@"/Users/apple/Desktop/tesk.txt" atomically:YES];    //2、从之前保存的文件读取数据到字典对象  NSDictionary *dict4=[NSDictionary dictionaryWithContentsOfFile:@"/Users/apple/Desktop/tesk.txt"];  NSLog(@"dict4:%@",dict4);

(3)字典对象元素的访问

 1   //1、分别获取字典的所有键、值 2   NSArray *allkeys=[dict1 allKeys]; 3   NSLog(@"allkeys:%@",allkeys); 4   NSArray *allvalues=[dict1 allValues]; 5   NSLog(@"allvalues:%@",allvalues); 6    7   //2、通过指定的key取对应的value对象,没有这个key的话.返回nil 8   NSNumber *num1 = [dict1 objectForKey:@"key1"]; 9   NSNumber *num2 = [dict1 objectForKey:@"key5"];10   NSLog(@"%@",num1);11   NSLog(@"%@",num2);12   13   //3、获取字典中键值对的个数14   NSUInteger paircount=[dict2 count];15   NSLog(@"%lu",paircount);

(4)字典的遍历

1   for (id key in dict1) {2     id value=[dict1 objectForKey:key];3     NSLog(@"%@=%@",key,value);4   }

2015-04-07 21:17:53.933 NSDictionary[5465:226991] dict01:{  value0 = key0;  value1 = key1;  value2 = key2;}2015-04-07 21:17:53.934 NSDictionary[5465:226991] dict1:{  key0 = 123;  key1 = 456;  key2 = 678;}2015-04-07 21:17:53.934 NSDictionary[5465:226991] dict02:{  hong = name0;  wang = name1;  zhao = name2;}2015-04-07 21:17:53.934 NSDictionary[5465:226991] dict2:{  name0 = hong;  name1 = wang;  name2 = zhao;}2015-04-07 21:17:53.935 NSDictionary[5465:226991] dict03:{  key0 = 123;  key1 = 456;  key2 = 678;}2015-04-07 21:17:53.935 NSDictionary[5465:226991] dict3:{  key0 = 123;  key1 = 456;  key2 = 678;}2015-04-07 21:17:53.937 NSDictionary[5465:226991] dict4:{  key0 = 123;  key1 = 456;  key2 = 678;}2015-04-07 21:17:53.938 NSDictionary[5465:226991] allkeys:(  key1,  key0,  key2)2015-04-07 21:17:53.938 NSDictionary[5465:226991] allvalues:(  456,  123,  678)2015-04-07 21:17:53.938 NSDictionary[5465:226991] num1:4562015-04-07 21:17:53.938 NSDictionary[5465:226991] num2:(null)2015-04-07 21:17:53.938 NSDictionary[5465:226991] 键值对个数:32015-04-07 21:17:53.938 NSDictionary[5465:226991] key1=4562015-04-07 21:17:53.938 NSDictionary[5465:226991] key0=1232015-04-07 21:17:53.938 NSDictionary[5465:226991] key2=678

运行结果分析

二、可变数据字典

    //可变数据字典初始化

    NSMutableDictionary *mDict1=[NSMutableDictionary dictionaryWithObjectsAndKeys:@"aaa",@"name0",@"bbb",@"name1",@"ccc",@"name2", nil];

    NSLog(@"%@",mDict1);

    

    //1、加入元素到NSMutableDictionary中  (注意:当key值中存在要添加的键值对中的key值时,则添加,否则覆盖)

    [mDict1 setObject:@"ddd" forKey:@"name3"];

    [mDict1 setObject:@"eee" forKey:@"name1"];

    NSLog(@"add:  %@",mDict1);

    

    //2、查看 中所有元素个数:

    NSLog(@"%lu",mDict1.count);

    NSNumber *num3 =[mDict1 objectForKey:@"name1"];

    NSLog(@"%@",num3);

    NSNumber *num4 = [mDict1 objectForKey:@"name10"];

    NSLog(@"%@",num4);

    

    //3、添加其他NSMutableDictionary

    [mDict1 setValuesForKeysWithDictionary:dict1];

    NSLog(@"++++%@",mDict1);

    

    //4、根据key值删除

    [mDict1 removeObjectForKey:@"name1"];

    NSLog(@"---%@",mDict1);

    //5、删除所有

    [mDict1 removeAllObjects];

    NSLog(@"%@",mDict1);

 

 

2015-04-07 22:12:10.717 NSDictionary[5827:248322] add: {  name0 = aaa;  name1 = eee;  name2 = ccc;  name3 = ddd;}2015-04-07 22:12:10.718 NSDictionary[5827:248322] 42015-04-07 22:12:10.718 NSDictionary[5827:248322] eee2015-04-07 22:12:10.718 NSDictionary[5827:248322] (null)2015-04-07 22:12:10.719 NSDictionary[5827:248322] ++++{  key0 = 123;  key1 = 456;  key2 = 678;  name0 = aaa;  name1 = eee;  name2 = ccc;  name3 = ddd;}2015-04-07 22:12:10.719 NSDictionary[5827:248322] ---{  key0 = 123;  key1 = 456;  key2 = 678;  name0 = aaa;  name2 = ccc;  name3 = ddd;}2015-04-07 22:12:10.719 NSDictionary[5827:248322] {}

运行结果分析