一奢人、NSDictionary基本概念
NSDictionary的作用類似：通過一個key，就能找到對應(yīng)的Value
NSDictionary是一個不可變的，一旦初始化后，就無法修改
二萨蚕、NSDictionary的創(chuàng)建
- 方法一：
- 創(chuàng)建一個dictionaryWithObject
- 創(chuàng)建多個dictionaryWithObjects
NSDictionary *dict = [NSDictionary dictionaryWithObject:@"lm" forKey:@"name"];
NSString *name = [dict objectForKey:@"name"];
- 方法二：簡單方法
- NSDictionary *dict = @{key1:value1,key2:value2};
NSDictionary *dict = @{@"lm":@"name",@"25":@"age",@"160":@"height"};
三、如何獲取
- 方法一：objectForKey
NSString *name = [dict objectForKey:@"name"];
- 方法二：NSLog(@"%@", dict[@"name"]);
四涉馁、字典的遍歷
如何獲取字典中key和value的個數(shù),
在字典中key稱之為鍵, value稱之為值
NSLog(@"count = %lu", [dict count]);
方法一：for循環(huán)【不用】
for (int i = 0; i < dict.count; ++i) {
// 獲取字典中所有的key
NSArray *keys = [dict allKeys];
// 取出當(dāng)前位置對應(yīng)的key
// NSLog(@"%@", keys[i]);
NSString *key = keys[i];
NSString *value = dict[key];
NSLog(@"key = %@, value = %@", key, value);
}
- 方法二：forin遍歷字典【不用】
for (NSString *key in dict) {
// NSLog(@"%@", key);
NSString *value = dict[key];
NSLog(@"key = %@, value = %@", key, value);
}
- 方法三：迭代器遍歷enumerateKeysAndObjectsUsingBlock
NSDictionary *dict = @{@"lm":@"name",@"25":@"age",@"160":@"height"};
[dict enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, id _Nonnull obj, BOOL * _Nonnull stop) {
NSLog(@"obj:%@, key:%@", obj, key);
}];
五门岔、字典文件讀寫
- 字典讀取writeToFile
- 字典寫入dictionaryWithContentsOfFile
[dict writeToFile:@"/Users/jeffrey/Desktop/php.plist" atomically:YES];
NSDictionary * dict = [NSDictionary dictionaryWithContentsOfFile:@"/Users/jeffrey/Desktop/php.plist"];
六、NSMutableDictionary
- 1.創(chuàng)建一個空的字典
NSMutableDictionary *dictM = [NSMutableDictionary dictionary];
```objc
- 2.如何添加
```objc
[dictM setObject:@"lm" forKey:@"name"];
// 會將傳入字典中所有的鍵值對取出來添加到dictM中
[dictM setValuesForKeysWithDictionary:@{@"age":@"30", @"height":@"1.75"}]
```objc
- 3.如何獲取
```objc
NSLog(@"%@", dictM[@"lm"]);
- 4.如何刪除
[dictM removeObjectForKey:@"lm"];
- 5.如何修改
- 如果利用setObject方法給同名的key賦值, 那么新值會覆蓋舊值
[dictM setObject:@"88" forKey:@"age"];
dictM[@"age"] = @"88";
