《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 }