Object c字典对象

本节学习内容:

1.字典的概念

2.字典的创建及初始化

3.字典的操作

4.可变字典的创建及初始化

5.可变典的操作

【main.m】

#import<Foundation/Foundation.h>

【1.字典的概念】

//NSDictionary 创建不可变字典对象的类

//字典对象中的元素都是键值对，key:value

//字典中的元素没有顺序

//NSMutableDictionary 创建可变字典对象，继承于NSdictionary

//可以使用所有的不可变字黄类中的方法

//对于可变子典对象，可以进行添加，修改，删除操作

//在字典对象中，key的值是唯一，value的值可以相同

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

@autoreleasepool{

【2.字典的创建及初始化】

1.创建一个不可变对象

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

NSLog(@“dict=%@”,dict);

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

2.用传入键值对创建值对初始化字典对象，key与值要相对应

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

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

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

3.用传入的字典初始化字典

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

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

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

4.用传入值的数组，及传入的key的数组创建字典对象，要求值的数组与key的数组要对应

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

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

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

5.创建空的字典对象

NSDictionary *dict4=[[NSDictionar alloc]init]

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

//打印结果: dict4=()

5.类方法创建字典对象,创建空的字典对象

NSDictionary *dict5=[[NSDictionar dictionary];

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

//打印结果: dict5=()

6.类方法用传的键值创建字典对象

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

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

//打印结果: dict4=(five=5,seven=7,six=6)

7.类方法用传的字典对象创建字典对象

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

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

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

8.类方法用传的值数组与key数组创建字典对象

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

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

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

【3.字典的操作】

1.获取字典对象中键值对的个数

NSInteger count=[dict count];

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

//打印结果: count = 4

2.通过key获取字典中key对应的值

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

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

//打印结果: obj = 3

3.获取所有的values

NSArray *valueArray=[dict alValues];

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

//打印结果: keyArray= (1,3,2,4)

3.获取所有的key

NSArray *keyArray=[dict allkeys];

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

//打印结果: keyArray= (one,three,two ,four)

4.判断两个字典对象是否相等

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

if(ret){

NSLog(@"字典对象相等");

}else{

NSLog(@"字典对象不相等");

}

//打印结果：字典对象不相等

5.字典的遍历[枚举器法]

NSEnumerator *keyEnumerator=[dic KeyEnumerator];

id obj2=nil;

while(obj2=[keyEnumerator nextObject]){

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

｝

//打印结果 key= one value=1,key= three value=3,key= two value=2, key= four value=4

6遍历字典 [快速枚举法]

for(id obj3 in dict){

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

}

//打印结果 key= one value=1,key= three value=3,key= two value=2, key= four value=4

【4.可变字典的创建及初始化】

1.可变字典操作[构造指定容量大小的可变字典对象]

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

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

//打印结果：mulDict=（）

2.可变数组操作[类方法创建指定容量大小的可变字典对象]

NSMutableDictionary *mulDict1 =[NSMutableDictionary dictionaryWithCapacity:20];

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

//打印结果：mulDict1=（）

【5.可变字典的操作】

1.可变数组操作[删除键值对]

NSMutableDictionary *mulDict3 =[NSMutableDictionary dictionaryWithDictionary:dict];