《慕客网：IOS基础入门之Foundation框架初体验》学习笔记 <五> NSDicionary + NSMutableDictionary

 1 int main(int argc, const char * argv[]) {
 2  @autoreleasepool {
 3 //字典， 存储的内存不是连续的 用key和value进行对应(键值)
 4 //kvc 键值编码  5 NSDictionary *dic = [NSDictionary dictionaryWithObject:@"1" forKey:@"a"];
 6 NSLog(@"%@",dic);//以上的方法是不常用的
 7 //注意两个参数是数组
 8 //NSDictionary *dic2 = [NSDictionary dictionaryWithObjects:<#(NSArray *)#> forKeys:<#(NSArray *)#>]
 9 //所以还是要先创建两个数组 10 NSArray *array1 = [[NSArray alloc] initWithObjects:@"a",@"b",@"c",@"d", nil];
11 NSArray *array2 = [[NSArray alloc] initWithObjects:@"1",@"2",@"3",@"4", nil];
12 NSDictionary *dic2 = [[NSDictionary alloc] initWithObjects:array1 forKeys:array2];
13 NSLog(@"%@",dic2);
14 //
15 NSDictionary *dic3 = @{@"m":@"9",@"n":@"8"};
16 NSLog(@"%@",dic3);
17 //输出字典的长度 18 int count = (int)[dic3 count];
19 NSLog(@"%d",count);
20 //通过键 获得 值 21 NSString *str = [dic3 valueForKey:@"m"];//或者[dic3 objectForKey:@"m"] 22 NSLog(@"%@",str);
23 //获取所有键值中的键和值 24 NSArray *allValue = [dic3 allValues];
25 NSArray *allKey = [dic3 allKeys];
26 //通过多个键找值，因为是多个，当然返回的是数组 27 NSArray *array = [dic2 objectsForKeys:[NSArray arrayWithObjects:@"2",@"3",@"9", nil] notFoundMarker:@"not found"];
28 NSLog(@"%@",array);
29 //遍历字典，数组通过下标遍历，字典当然通过key来遍历 30 for (NSString *key in dic2) {
31 NSLog(@"%@ = %@",key,[dic2 objectForKey:key]);
32  }
33 //使用针对字典的枚举器 34 NSEnumerator *en = [dic2 keyEnumerator];
35 id key = nil;
36 while (key = [en nextObject]) {
37 NSLog(@"key - %@",key);
38  }
39 //还有一个block方法，用法都是一样的 40 /* 41  [dic2 enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
42 43  }];*/ 44  }
45 return 0;
46 }

 1 int main(int argc, const char * argv[]) {
 2  @autoreleasepool {
 3 NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
 4 //添加键值对，直接添加就可以了  5 [dict setObject:@"1" forKey:@"a"];
 6 [dict setObject:@"2" forKey:@"b"];
 7 [dict setObject:@"3" forKey:@"c"];
 8 NSLog(@"%@",dict);
 9 //删除键值对 10 [dict removeObjectForKey:@"a"];
11 NSLog(@"%@",dict);
12 //还可以通过传入数组对象，对应删除数组元素对应的所有键 13 [dict removeObjectsForKeys:[NSArray arrayWithObjects:@"a",@"c", nil]];
14 NSLog(@"%@",dict);
15  }
16 return 0;
17 }