Foundation ----->NSDictionary
2024-10-16 04:59:03
/*_______________不可变字(NSDictionary)____________*/
//1.字典的创建
//值(value)
NSArray *array1 = @[@"zhangsan",@"zhangfei",@"zhangchaoyang"]; //zhang
NSArray *array2 = @[@"lisi",@"lining",@"lilei"]; //li
//两个元素:zhang:array1 li:array2
NSDictionary *dic1 = [[NSDictionary alloc] initWithObjectsAndKeys:array1,@"zhang",array2,@"li", nil];
// NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:<#(nonnull id), ...#>, nil]
NSLog(@"dic1:%@",dic1);
//通过已有的字典给现在的字典初始化
NSDictionary *dic2 = [[NSDictionary alloc] initWithDictionary:dic1];
NSLog(@"dic2:%@",dic2);
//2.获取字典中的元素个数
NSUInteger count = dic1.count;
NSLog(@"count:%ld",count);
//3.获取字典中的所有key(键)
NSArray *keys = [dic1 allKeys];
NSLog(@"key:%@",keys);
//4.获取所有的value(值)
NSArray *values = [dic1 allValues];
NSLog(@"values:%@",values);
//5.通过key取得对应的value
NSArray *value = [dic1 objectForKey:@"zhang"];
NSLog(@"value:%@",value);
//注意:在字典中key唯一,但是value可以相同
NSDictionary *dic3 = [[NSDictionary alloc] initWithObjectsAndKeys:array1,@"zhang",array2,@"li",array1,@"li1", nil];
NSLog(@"%@",dic3);
/*____________________优化语法___________________________*/
//初始化
NSDictionary *dic4 = @{
@"zhang":array1,
@"li":array2
};
NSLog(@"dic:%@",dic4); //根据key获取vlaue
NSArray *v = dic4[@"zhang"];
NSLog(@"v:%@",v);
/*______________可变字典(NSMutableDictionary)________*/
//创建可变字典
NSMutableDictionary *mutDic1 = [[NSMutableDictionary alloc] initWithCapacity:];
//1.添加元素
// [mutDic1 setObject:array1 forKey:@"zhang"];
// [mutDic1 setObject:array2 forKey:@"li"];
//注意:如果在添加键值对的时候,如果添加了已有的key,则会覆盖以前的数据
// [mutDic1 setObject:@"liyoubing" forKey:@"li"];
//将dic1中的所有键值对添加到mutDic1
[mutDic1 addEntriesFromDictionary:dic1];
//2.删除
//删除所有元素
// [mutDic1 removeAllObjects];
//根据key删除
// [mutDic1 removeObjectForKey:@"li"];
//根据多个key删除数据
// [mutDic1 removeObjectsForKeys:@[@"li",@"zhang"]];
NSLog(@"mutDic1:%@",mutDic1);
//----------字典的遍历---------- //方式一
//获取所有的key
NSArray *keyArray = mutDic1.allKeys;
for (int i=; i<keyArray.count; i++) {
//1.获取指定的key
NSString *key = keyArray[i];
//2.根据key->value
// mutDic1 objectForKey:<#(nonnull id)#>
NSArray *value = mutDic1[key];
NSLog(@"key:%@ value:%@",key,value);
}
//方式二:快速遍历
for (NSString *key in mutDic1) {
//根据key->value
NSArray *value = [mutDic1 objectForKey:key];
NSLog(@"key:%@ vlaue:%@",key,value);
}
/*
字典是无序的
*/
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