OC语言基础之NSDictionary

1.NSDictionary字典的创建

   1:  // key value

   2:      // key -==> value

   3:      NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"key"];

   4:      

   5:      NSArray *keys = [NSArray arrayWithObjects:@"k1", @"k2", nil];

   6:      NSArray *values = [NSArray arrayWithObjects:@"v1", @"v2", nil];

   7:      NSDictionary *dict1 = [NSDictionary dictionaryWithObjects:values

   8:                                                        forKeys:keys];

   9:      NSDictionary *dict2 = [NSDictionary dictionaryWithObjectsAndKeys:@"v", @"key",

  10:                             @"v1", @"key1",

  11:                             nil];

  12:      NSLog(@"%@", dict2);

  13:      

  14:      

  15:      //    BOOL isSuccess = [dict writeToFile:@"/Users/apple/Desktop/1.txt"

  16:      //           atomically:YES];

  17:      //    if (isSuccess) {

  18:      //        NSLog(@"成功");

  19:      //    }else{

  20:      //        NSLog(@"写入失败");

  21:      //    }

  22:      

  23:      NSDictionary *dict3 = [NSDictionary dictionaryWithContentsOfFile:@"/Users/apple/Desktop/1.txt"];

  24:      NSLog(@"%@", dict3);

字典的遍历

   1:   NSDictionary *pDict = [NSDictionary dictionaryWithObjectsAndKeys:@"abc", @"name",

   2:                             @"11", @"age",

   3:                             @"男", @"gender",

   4:                             nil];

   5:      //    NSArray *keys = [pDict allKeys];

   6:      //    for (int i = 0; i<[pDict count]; i++) {

   7:      //        NSString *key = [keys objectAtIndex:i];

   8:      //        NSString *value = [pDict objectForKey:key];

   9:      //        NSLog(@"%@: value= %@", key, value);

  10:      //    }

  11:      

  12:      //    for (id key in pDict) {

  13:      //        NSLog(@"%@", key);

  14:      //    }

  15:      //

  16:      

  17:      [pDict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {

  18:          NSLog(@"%@", key);

  19:          

  20:          // 修改stop指向内存的值

  21:          *stop = YES;

  22:      }];

2.可变字典

   1:   

   2:      NSMutableDictionary *dictM = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"v", @"key",

   3:                                    nil];

   4:      [dictM setObject:@"1" forKey:@"key"];

   5:      NSLog(@"%@", dictM);

3.具体使用的例子

   1:  // 名字

   2:      // 年龄

   3:      // 性别

   4:      NSDictionary *pDict = [NSDictionary dictionaryWithObjectsAndKeys:

   5:                             @"11", @"age",

   6:                             @"abc", @"name",

   7:                             @"男", @"gender",

   8:                             nil];

   9:      

  10:      

  11:      //    NSMutableArray *array = [NSMutableArray array];

  12:      //    [array addObject:pDict];

  13:      

  14:      id name = [pDict objectForKey:@"name"];

  15:      NSLog(@"%@", name);

4.各常用类对比

   1:  /*

   2:   集合

   3:   1.NSArray\NSMutableArray

   4:   * 有序

   5:   * 快速创建（不可变）：@[obj1, obj2, obj3]

   6:   * 快速访问元素：数组名[i]

   7:  

   8:   2.NSSet\NSMutableSet

   9:   * 无序

  10:  

  11:   3.NSDictionary\NSMutableDictionary

  12:   * 无序

  13:   * 快速创建（不可变）：@{key1 : value1,  key2 : value2}

  14:   * 快速访问元素：字典名[key]

  15:   */

例子

   1:   /*

   2:       字典：

   3:  

   4:       key ----> value

   5:       索引 ----> 文字内容

   6:  

   7:       里面存储的东西都是键值对

   8:  

   9:  

  10:       */

  11:      

  12:      // NSDictionary *dict = [NSDictionary dictionaryWithObject:@"jack" forKey:@"name"];

  13:      

  14:      

  15:      // NSArray *keys = @[@"name", @"address"];

  16:      // NSArray *objects = @[@"jack", @"北京"];

  17:      

  18:      // NSDictionary *dict = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

  19:      

  20:      

  21:      /*

  22:       NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:

  23:       @"jack", @"name",

  24:       @"北京", @"address",

  25:       @"32423434", @"qq", nil];*/

  26:      

  27:      

  28:      NSDictionary *dict = @{@"name" : @"jack", @"address" : @"北京"};

  29:      

  30:      // id obj = [dict objectForKey:@"name"];

  31:      

  32:      id obj = dict[@"name"];

  33:      

  34:      NSLog(@"%@", obj);

  35:      

  36:      

  37:      

  38:      // 返回的是键值对的个数

  39:      NSLog(@"%ld", dict.count);