字典 nsdictionary
1.概念字典是關鍵字'key'及其定義的值(value)所構成的集合，即它是由key-value組成的鍵值對的集合。
'key'一般是'nsstring'型別的，『value』是oc中任意物件。對於字典來講，我們就是通過'key'來訪問 'value'。
2.為什麼在有了陣列之後還需要字典？在有大量的資料或者頻繁的查詢的時候，使用字典效率更高。
因為字典才用鍵查詢的優化儲存方式。
nsdictionary *dictionary1 = [[nsdictionary alloc]init];
nsdictionary *dictionary2 = [nsdictionary dictionary];
nsdictionary *dictionary3 = [nsdictionary dictionarywithobject:@"leee" forkey:@"name"];nsdictionary *dictionary4 = [nsdictionary dictionarywithobjectsandkeys:@"leee",@"name",@25,@"age",@"gz",@"address", nil];nsdictionary *dictionary5 = [nsdictionary dictionarywithdictionary:dictionary4];
nslog(@"%@",dictionary5);
nsdictionary *dictionary6 = @{};nsdictionary *dictionary7 = @;nsdictionary *dictionary8 = @;nsdictionary *dictionary9 = [nsdictionary dictionarywithcontentsoffile:@""];
nsdictionary *dictionary10 = [nsdictionary dictionarywithcontentsofurl:[nsurl urlwithstring:@""]];
nsuinterger count = dictionary.count;通過key訪問字典中的值
nsstring *name = [dictionary4 objectforkey:@"name"];nsstring *newname = dictionary4 [@"name"];表示字典裡所有的key
nsarray *keysarray = dictionary4.allkeys;
nsarray *valuesarray = [dictionary4.allvalues];
for (int i =0;i forin
for (nsstring *key in keysarray)
nsenumerator *enumerator = [keysarray objectenumerator];
id key
while (key =[enumerator nextobject])
for(nsstring *str in dictionary.allkeys)
建立乙個空的字典
nsmutabledictionary *mdictionary1 = [nsmutabledictionary dictionary];nsmutabledictionary *mdictionary2 = [nsmutabledicitionary dictionarywithobject:@"leee", forkey:@"name"];nsmutablediction *mdictionary3 = [nsmutabledictionary dictionarywithobjectandkeys:@"leee",@"name",@25,@"age",@"gz",@"address",nil];nsmutabledictionary *mdictionary4 = [nsmutabledictionary dictionarywithdictionary:mdictionary3];nsmutabledictionary *mdictionary5 = [nsmutabledictionary dictionarywithcapacity:10];增
[mdictionary5 setvalue:@"leee" forkey:@"name"];
[mdictionary5 setvalue:@25 forkey:@"name"];
[mdictionary5 setvalue:@"sb" forkey:@"name"];刪除指定key 的物件
[mdictionary5 removeobjectforkey:@"name"];
[mdicitonary5 removeallobjects];
nsmutabledicitonary *mdic8 = [nsmutabledicitonary dictionarywithobjectandkeys:@"leee",@"name1",@22,@"age",@"gz",@"address",@"leee",@"name2",@"leee",@"name3",nil];oc75 不可變字典NSDictionary
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