IOS Intro - NSDictionary and NSMutableDictionary

1.不可变词典NSDictionary

字典初始化

NSNumber *numObj = [NSNumber numberWithInt:100];

以一个元素初始化

NSDictionary *dic = [NSDictionary dictionaryWithObject:numObj forKey:@"key"];

初始化两个元素

NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:numObj, @"valueKey", numObj2, @"value2",nil];

初始化新字典，新字典包含otherDic

NSDictionary *dic = [NSDictionary dictionaryWithDictionary:otherDic];

以文件内容初始化字典

NSDictionary *dic = [NSDictionary dictionaryWithContentsOfFile:path];

常用方法

获取字典数量

NSInteger count = [dic count];

通过key获取对应的value对象

NSObject *valueObj = [dic objectForKey:@"key"];

将字典的key转成枚举对象，用于遍历

NSEnumerator *enumerator = [dic keyEnumerator];

获取所有键的集合

NSArray *keys = [dic allKeys];

获取所有值的集合

NSArray *values = [dic allValues];

2.可变数组NSMutableDictionary

初始化一个空的可变字典

NSMutableDictionary *dic2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"v1",@"key1",@"v2",@"key2",nil];

NSDictionary *dic3 = [NSDictionary dictionaryWithObject:@"v3" forKey:@"key3"];

向字典2对象中添加整个字典对象3

[dic2 addEntriesFromDictionary:dic3];

向字典2对象中最佳一个新的key3和value3

[dic2 setValue:@"value3" forKey:@"key3"];

初始化一个空的可变字典

NSMutableDictionary *dic1 = [NSMutableDictionary dictionary];

将空字典1对象内容设置与字典2对象相同

[dic1 setDictionary:dic2];

将字典中key1对应的值删除

[dic1 removeObjectForKey@"key1"];

NSArray *array = [NSArray arrayWithObjects:@"key1", nil];

根据指定的数组（key）移除字典1的内容

[dic2 removeObjectsForKeys:array];

移除字典所有对象

[dic1 removeAllObjects];

遍历字典

快速枚举

for (id key in dic){

     id obj = [dic objectForKey:key];

     NSLog(@"%@", obj);

}

一般枚举

NSArray *keys = [dic allKeys];

inr length = [keys count];

for (int i = 0; i < length；i++){

     id key = [keys objectAtIndex:i];

     id obj = [dic objectForKey:key];

     NSLog(@"%@", obj);

}

通过枚举类型枚举

NSEnumerator *enumerator = [dic keyEnumerator];

id key = [enumerator nextObject];

while (key) {

        id obj = [dic objectForKey:key];

        NSLog(@"%@", obj);

        key = [enumerator nextObject];

}