Object c字典對象

本節學習內容:

1.字典的概念

2.字典的創建及初始化

3.字典的操作

4.可變字典的創建及初始化

5.可變典的操作

【main.m】

#import<Foundation/Foundation.h>

【1.字典的概念】

//NSDictionary 創建不可變字典對象的類

//字典對象中的元素都是鍵值對，key:value

//字典中的元素沒有順序

//NSMutableDictionary 創建可變字典對象，繼承于NSdictionary

//可以使用所有的不可變字黃類中的方法

//對于可變子典對象，可以進行添加，修改，刪除操作

//在字典對象中，key的值是唯一，value的值可以相同

int main(int argc,const char*argv[]){

@autoreleasepool{

【2.字典的創建及初始化】

1.創建一個不可變對象

NSDictionary *dict=@{@"one":@"1",@"two":@"0"
,@"three":@"3",@"four":@"4"}

NSLog(@“dict=%@”,dict);

//打印結果= dict=(four=4;one=1,tree=3,two=2)

2.用傳入鍵值對創建值對初始化字典對象，key與值要相對應

NSDictionary *dict1=[[NSDictionar allic]initWithObjectsAndKeys:@"9",@"nine",@"eight",@"7",@"seven",nil];

NSLog[@"dict1=%@",dict1];

//打印結果: dict1=(eight=8;one=1,nine=9,seven=7)

3.用傳入的字典初始化字典

NSDictionary *dict2=[[NSDictionar alloc]initWithDictionary:dict];

NSLog[@"dict2=%@",dict2];

//打印結果: dict2=(four=4;one=1,tree=3,two=2)

4.用傳入值的數組，及傳入的key的數組創建字典對象，要求值的數組與key的數組要對應

NSDictionary *dict3=[[NSDictionar alloc]initWithObjects:[NSArray arrayWithObjects:@"1",@"2",@"2",@"4",nil] forKeys:[NSArray arrayWithObjects:@"one",@"two",@"three",@"for",nil]];

NSLog[@"dict3=%@",dict3];

//打印結果: dict2=(four=4;one=1,tree=3,two=2)

5.創建空的字典對象

NSDictionary *dict4=[[NSDictionar alloc]init]

NSLog[@"dict4=%@",dict4];

//打印結果: dict4=()

5.類方法創建字典對象,創建空的字典對象

NSDictionary *dict5=[[NSDictionar dictionary];

NSLog[@"dict5=%@",dict5];

//打印結果: dict5=()

6.類方法用傳的鍵值創建字典對象

NSDictionary *dict6=[[NSDictionar dictionaryWithObjectsKeys:@"5",@"five",@"six",@"7",@"seven",nil];

NSLog[@"dict6=%@",dict6];

//打印結果: dict4=(five=5,seven=7,six=6)

7.類方法用傳的字典對象創建字典對象

NSDictionary *dict7=[[NSDictionar dictionaryWithDictionary:dict];

NSLog[@"dict7=%@",dict7];

//打印結果: dict7=(four=4;one=1,tree=3,two=2)

8.類方法用傳的值數組與key數組創建字典對象

NSDictionary *dict8=[NSDictionary dictionaryWithObjects:@"1",@"3",@"5",@"6"] forKeys:@[@"one",@"three",@"five",@"six"]]

NSLog[@"dict8=%@",dict8];

//打印結果: dict8=(five=5;one=1,six=6,three=3)

【3.字典的操作】

1.獲取字典對象中鍵值對的個數

NSInteger count=[dict count];

NSLog(@"count = %li",count);

//打印結果: count = 4

2.通過key獲取字典中key對應的值

id obj=[dict objectForKey:@"three"]

NSLog(@"obj = %@",obj);

//打印結果: obj = 3

3.獲取所有的values

NSArray *valueArray=[dict alValues];

NSLog(@"valueArray= %@",valueArray);

//打印結果: keyArray= (1,3,2,4)

3.獲取所有的key

NSArray *keyArray=[dict allkeys];

NSLog(@"keyArray= %@",keyArray);

//打印結果: keyArray= (one,three,two ,four)

4.判斷兩個字典對象是否相等

Bool ret=[dict isEqualToDictionary:@{@"one":@"1",@"two":@"2",@"three":@"3"}];

if(ret){

NSLog(@"字典對象相等");

}else{

NSLog(@"字典對象不相等");

}

//打印結果：字典對象不相等

5.字典的遍歷[枚舉器法]

NSEnumerator *keyEnumerator=[dic KeyEnumerator];

id obj2=nil;

while(obj2=[keyEnumerator nextObject]){

NSLog(@"key"=%@ value=%@",obj2,[dict objectForKey:obj2]);

｝

//打印結果 key= one value=1,key= three value=3,key= two value=2, key= four value=4

6遍歷字典 [快速枚舉法]

for(id obj3 in dict){

NSLog(@"key"=%@ value=%@",obj3,[dict objectForKey:obj3]);

}

//打印結果 key= one value=1,key= three value=3,key= two value=2, key= four value=4

【4.可變字典的創建及初始化】

1.可變字典操作[構造指定容量大小的可變字典對象]

NSMutableDictionary *mulDict =[NSMutableDictionary alloc] initWitCapacity:20];

NSLog(@"mulDict = %@",mulDict);

//打印結果：mulDict=（）

2.可變數組操作[類方法創建指定容量大小的可變字典對象]

NSMutableDictionary *mulDict1 =[NSMutableDictionary dictionaryWithCapacity:20];

NSLog(@"mulDict1= %@",mulDict1);

//打印結果：mulDict1=（）

【5.可變字典的操作】

1.可變數組操作[刪除鍵值對]

NSMutableDictionary *mulDict3 =[NSMutableDictionary dictionaryWithDictionary:dict];