标签：实例 排序 val 定义 and key值 color sar log
简介：字典是一种数据结构，字典里面的每一个元素，是一个key-value（键值对），key和value都是对象类型。同NSArray一样，里面的对象不用保持一致性。
1、字面量初始化
// 存储时时无序的 NSDictionary *dict = @{@"name" : @"xiaoming", @"gendar" : @"man", @"age" : @"19"}; // 打印时根据Unicode码排序打印 NSLog(@"%@", dict);
2、实例方法初始化
NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", nil];
3、类方法初始化
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", nil];
4、打印key-value的对数
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", nil]; NSLog(@"%@", dict.count);
注意：key-value键值对中的key具有唯一性，value可以相同。也就是说，栗子如下：
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", @"woman", @"gendar", nil]; NSLog(@"%@", dict); ====打印 { age = 19; gendar = man; name = xiaoming; }
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", @"man", @"lastGendar", nil]; NSLog(@"%@", dict); ====打印 { age = 19; gendar = man; lastGendar = man; name = xiaoming; }
5、根据key取出相应的value
NSDictionary *dict = @{@"name" : @"xiaoming", @"gendar" : @"man", @"age" : @"19"};
// valueForKey是NSDictionary的分类中的一个方法
NSString *nameString = [dict valueForKey:@"name"];
// objectForKey是NSDictionary本身定义的一个方法
NSString *ageString = [dict objectForKey:@"age"];
// 根据下标符取出value
NSString *gendarString = dict[@"gendar"];
NSLog(@"~~~~~~~~~~%@~~~~~~~~~~%@~~~~~~~~~~%@", nameString, ageString, gendarString);
====打印
~~~~~~~~~~xiaoming~~~~~~~~~~19~~~~~~~~~~man
6、取出字典中所有的key、所有的value
NSDictionary *dict = @{@"name" : @"xiaoming", @"gendar" : @"man", @"age" : @"19"};
NSArray *keyArray = [dict allKeys];
NSArray *valueArray = [dict allValues];
NSLog(@"\n%@\n%@", keyArray, valueArray);
====打印
(
name,
gendar,
age
)
(
xiaoming,
man,
19
)
7、判断两个字典对象是否相同
NSDictionary *dict1 = @{@"name" : @"小明", @"gendar" : @"男", @"age" : @"19"};
NSDictionary *dict2 = @{@"name" : @"小红", @"gendar" : @"男", @"age" : @"19"};
BOOL bo = [dict1 isEqualToDictionary:dict2];
NSLog(@"%@", bo ? @"两者相同" : @"两者不相同");
====打印
两者不相同
1、构建方法初始化
NSMutableDictionary *mDict = [[NSMutableDictionary alloc] init];
2、类方法初始化
NSMutableDictionary *mDict = [NSMutableDictionary dictionary];
3、根据key值修改对应的value（找不到对应的key，就相当于添加这一对key-value）
NSMutableDictionary *mDict = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", @"woman", @"gendar", nil]; [mDict setObject:@"20" forKey:@"age"]; [mDict setObject:@"China" forKey:@"address"]; NSLog(@"%@", mDict); ====打印 { address = China; age = 20; gendar = woman; name = xiaoming; }
4、根据key删除key-value键值对
NSMutableDictionary *mDict = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", @"xiaoming", @"name", @"woman", @"gendar", nil]; [mDict removeObjectForKey:@"name"]; NSLog(@"%@", mDict); ====打印 { age = 19; gendar = woman; }
5、使用一个字典重置可变字典
NSMutableDictionary *dict1 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"19", @"age", @"man", @"gendar", nil]; NSMutableDictionary *dict2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"20", @"age", @"woman", @"gendar", nil]; [dict2 setDictionary:dict1]; NSLog(@"%@", dict2); ====打印 { age = 19; gendar = man; }
----未完待续
字典NSDictionary和NSMutableDictionary的使用
标签：实例 排序 val 定义 and key值 color sar log
原文地址：https://www.cnblogs.com/cchHers/p/9071467.html
