oc随笔六：字典

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //NSDictionary字典对象，字典主要特征是一对一的key和value组成
        //不可变字典
        //初始化字典，一半key值是字符串对象，控制用NSNull对象表示
        NSDictionary *dic1 = [NSDictionary dictionaryWithObject:@"velue1" forKey:@"key1"];
        NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:@"value2",@"key2",@"value3",@"key3",nil];
        NSDictionary *dic3 = [NSDictionary dictionaryWithDictionary:dic1];
        //值与键都为数组,需要注意的是value数组与key数组的元素个数要保持一致，因为字典都是键值对，要一一对应，nil不会计入字典数量中
        NSArray *arrValue = [NSArray arrayWithObjects:@"hello",@"world",@"!",@"test", nil];
        NSArray *arrKey = [NSArray arrayWithObjects:@"keyOne",@"keyTow",@"keyThree",@"keytest", nil];
        NSDictionary *dic4 = [NSDictionary dictionaryWithObjects:arrValue forKeys:arrKey];
        NSLog(@"%@",dic2);
        NSLog(@"%@",dic3);
        NSLog(@"%@",dic4);
        //获取字典的数量
        NSInteger count = [dic4 count];
        NSLog(@"%ld",count);
        //通过key获取value值
        NSObject *objNew = [dic2 objectForKey:@"key2"];
        NSLog(@"%@",objNew);
        NSObject *objtest = [dic4 objectForKey:@"keyOne"];
        NSLog(@"---------%@",objtest);
        //通过数组中的key匹配字典
        NSArray * test = [NSArray arrayWithObjects:@"keyOne",@"keyThree", nil];
        NSObject *objNew1 = [dic4 objectsForKeys:test notFoundMarker:@"error"];
        NSLog(@"%@",objNew1);
        //将字典的key变成一个枚举对象用于遍历
        NSEnumerator *enumerator = [dic4 keyEnumerator];
        //枚举遍历法(keyEnumerator)
        id key = [enumerator nextObject];
        while (key) {
            id object = [dic4 objectForKey:key];
            NSLog(@"%@",object);
            key = [enumerator nextObject];//不复写key的值，会陷入死循坏
        }
        //获取字典所有key集合
        NSArray *arrKey1 = [dic2 allKeys];
        NSLog(@"%@",arrKey1);
        //获取字典所有value集合
        NSArray *arrValue1 = [dic2 allValues];
        NSLog(@"%@",arrValue1);

        //可变字典
        //初始化可变字典
        NSMutableDictionary *mudic1 = [NSMutableDictionary dictionary];
        NSLog(@"%@",mudic1);//为空
        NSMutableDictionary *mudic2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2", nil];
        //把一个字典加入到另一个字典中(把mudic2添加到mudic1中)
        [mudic1 addEntriesFromDictionary:mudic2];
        NSLog(@"%@",mudic1);
        //给字典新添增元素
        [mudic1 setObject:@"Augus" forKey:@"key1"];
        NSLog(@"%@",mudic1);
        //把一个字典的内容设置为跟另一个字典内容相同(把mudic1的内容设置为mudic2一样)
        [mudic1 setDictionary:mudic2];
        NSLog(@"%@",mudic1);
        //移除字典元素
        [mudic1 removeObjectForKey:@"k2"];
        NSLog(@"%@",mudic1);
        //快速遍历方法
        for (id key in mudic2) {
            id objx = [mudic2 objectForKey:key];
            NSLog(@"%@",objx);
        }
        //常用遍历方法，首先获取到key的集合，然后通过遍历key集合来实现字典value的遍历
        NSArray *keyarr = [mudic2 allKeys];
        NSInteger num = [keyarr count];
        for (int i=0; i<num; i++) {
            id keyx = [keyarr objectAtIndex:i];
            id valuex = [mudic2 objectForKey:keyx];
            NSLog(@"%@",valuex);
        }
    }
    return 0;
}