OC菜鸟成长记-OC中的字典

下面笔者对自己有关OC中的字典的知识进行一下总结。在OC当中，字典的基本元素是由 键 和 值 组成的键值对。字典有不可变字典(NSDictionary)和可变字典(NSMutableDicitonary)两种。

首先是不可变字典(NSDictionary):

//初始化
NSDictionary *d1=[NSDictionary new];
NSDictionary *d2=[NSDictionary dictionaryWithObject:@"abcdefg" forKey:@"zimu"];
NSDictionary *d3=[NSDictionary dictionaryWithObjectsAndKeys:@"a",@"zimu",@"b",@"zimu",@"c",@"zimu", nil];
NSDictionary *d5=[NSDictionary dictionaryWithDictionary:d3];
//新语法
NSDictionary *d6=@{@"zimu":@"a",@"zimu":@"b"};

//键值对的数量
NSUInteger dcount = d3.count;
NSLog(@"dcount=%lu",dcount);

//访问字典
NSString *zimu=[d3 objectForKey:@"zimu"];
NSLog(@"zimu = %@ ",zimu);//字典中不存在相同的key
NSString *zimu2 =[d2 objectForKey:@"zimu"];
NSLog(@"zimu2=%@",zimu2);

//历遍字典
//字典有两部分：key和value
//需要使用数组进行接收
NSArray *dictionaryKey=d3.allKeys;
NSArray *dictionaryValue=d3.allValues;
for (id dkey in dictionaryKey) {
NSLog(@"dkey=%@",dkey);
}
NSEnumerator *denumerator = [dictionaryValue objectEnumerator];
id dobj;
while (dobj =[denumerator nextObject]) {
NSLog(@"dobj=%@",dobj);
}

运行结果是:

oc_731_practise[17787:164553] dcount=1
oc_731_practise[17787:164553] zimu = a
oc_731_practise[17787:164553] zimu2=abcdefg
oc_731_practise[17787:164553] dkey=zimu
oc_731_practise[17787:164553] dobj=a


然后是可变字典(NSMutableDicitonary):

// NSMutableDictionary
//初始化
NSMutableDictionary *md1=[[NSMutableDictionary alloc]init];
NSMutableDictionary *md2=[NSMutableDictionary dictionaryWithDictionary:d3];
NSMutableDictionary *md3=[NSMutableDictionary dictionaryWithObjectsAndKeys:@20,@"length",@10,@"width", nil];

//修改、增加
[md3 setObject:@30 forKey:@"height"];
NSLog(@"md3=%@",md3);
[md3 setObject:@60 forKey:@"length"];
NSLog(@"md3=%@",md3);
md3[@"width"]=@100;//新语法进行修改
NSLog(@"md3=%@",md3);
md3[@"point"]=@0;
NSLog(@"md3=%@",md3);//新语法进行添加

//删除
[md3 removeObjectForKey:@"point"];//删除一个元素 (键point 对应的值)
NSLog(@"md3=%@",md3);
[md3 removeObjectsForKeys:@[@"point",@"length"]];//删除多个元素 (键point 和length对应的值)
NSLog(@"md3=%@",md3);
[md3 removeAllObjects];//删除所有元素
NSLog(@"md3=%@",md3);


运行结果是:
oc_731_practise[17787:164553] md3={
height = 30;
length = 20;
width = 10;
}
oc_731_practise[17787:164553] md3={
height = 30;
length = 60;
width = 10;
}
oc_731_practise[17787:164553] md3={
height = 30;
length = 60;
width = 100;
}
oc_731_practise[17787:164553] md3={
height = 30;
length = 60;
point = 0;
width = 100;
}
oc_731_practise[17787:164553] md3={
height = 30;
length = 60;
width = 100;
}
oc_731_practise[17787:164553] md3={
height = 30;
width = 100;
}
oc_731_practise[17787:164553] md3={
}