NSDictionary字典创建,获取,遍历,可变字典的删除 - iOS

版权声明:本文为博主原创,如需转载请注明出处。

字典是以键值对的形式来存储数据 key value

1 NSDictionary 字典

1.1 创建字典,不可变的

1
2
NSDictionary * dic = [NSDictionary dictionaryWithObjectsAndKeys:@"xiaozhe",@"name", nil];
NSLog(@"dic %@",dic);
1
2
3
2016-08-14 14:44:17.460 07-字典类[2325:547877] dic {
name = xiaozhe;
}

1.2 快捷创建方式

1
2
NSDictionary * dic2 = @{ @"one":@"1",@"two":@"2"};
NSLog(@"dic2 %@",dic2);
1
2
3
4
2016-08-14 14:44:17.461 07-字典类[2325:547877] dic2 {
one = 1;
two = 2;
}

1.3 字典中可以存任意数据类型

字典的顺序不是自然顺序

1
2
3
4
5
6
7
8
9
10
11
12
NSArray * array = @[@"one",@"two"];

NSDictionary * dic3 = @{
@"one":@"1",
@"num":[NSNumber numberWithInt:10],
@"aaa":dic2,
@"bbb":dic,
@"ar1":array

};

NSLog(@"dic3 %@",dic3);
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
016-08-14 14:44:17.461 07-字典类[2325:547877] dic3 {
aaa = {
one = 1;
two = 2;
};
ar1 = (
one,
two
);
bbb = {
name = xiaozhe;
};
num = 10;
one = 1;
}

1.4 获得字典的长度

1
NSLog(@"count %ld",dic3.count);

1.5 从字典中取值

1
2
3
4
5
6
7
NSString * str  = [dic3 objectForKey:@"one"];
NSLog(@"str %@",str);

NSDictionary * dicTmp = [dic3 objectForKey:@"aaa"];
NSLog(@"dicTmp %@",dicTmp);
NSArray * arrayTmp = [dic3 objectForKey:@"ar1"];
NSLog(@"arrayTmp %@",arrayTmp);

1.6 遍历

取出所有的key值

1
2
3
4
5
6
7
8
9
10
11
NSArray * allkeys = [dic3 allKeys];
NSLog(@"allkeys %@",allkeys);

for (int i = 0; i < allkeys.count; i++)
{
NSString * key = [allkeys objectAtIndex:i];

//如果你的字典中存储的多种不同的类型,那么最好用id类型去接受它
id obj = [dic3 objectForKey:key];
NSLog(@"obj %@",obj);
}

枚举器

1
2
3
4
5
6
NSEnumerator * enumerator =  [dic3 objectEnumerator];

id value;
while (value = [enumerator nextObject]) {
NSLog(@"value %@",value);
}

2 NSMutableDictionary 可变字典

2.1 创建一个可变长度字典

1
NSMutableDictionary * muDic = [[NSMutableDictionary alloc] initWithCapacity:0];

2.2 向字典中存储数据

1
2
3
[muDic setObject:@"1" forKey:@"one"];
[muDic setObject:@"2" forKey:@"two"];
[muDic setObject:@"3" forKey:@"three"];

2.3 删除

1
[muDic removeObjectForKey:@"one"];

2.4 全部删除

1
[muDic removeAllObjects];

给一个 Student 类

1
2
3
4
5
6
7
8
@interface Student : NSObject

@property (nonatomic,assign) int age;
@property (nonatomic,strong) NSString * name;

- (id)initWithName:(NSString *)name andAge:(int)age;

@end
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

@implementation Student

- (id)initWithName:(NSString *)name andAge:(int)age
{
if (self = [super init])
{
_name = name;
_age = age;
}
return self;
}

- (NSString *)description
{
return [NSString stringWithFormat:@"name %@ age %d",_name,_age];
}

@end
1
2
3
4
5
6
7
8
9
10
11
Student * stu1 = [[Student alloc] initWithName:@"xiaoher" andAge:20];
Student * stu2 = [[Student alloc] initWithName:@"alex" andAge:50];
Student * stu3 = [[Student alloc] initWithName:@"xiaoli" andAge:10];

[muDic setObject:stu1 forKey:@"s1"];
[muDic setObject:stu2 forKey:@"s2"];
[muDic setObject:stu3 forKey:@"s3"];
//在向字典中存储数据的时候,一定要保证key值是唯一的
//[muDic setObject:stu3 forKey:@"s3"];
//[muDic setObject:stu3 forKey:@"s3"];
//[muDic setObject:stu3 forKey:@"s3"];

2.5 使用for循环遍历字典

1
2
3
4
5
6
7
8
NSArray * allkeys = [muDic allKeys];

for (int i = 0; i < allkeys.count; i++)
{
NSString * key = [allkeys objectAtIndex:i];
Student * stu = [muDic objectForKey:key];
NSLog(@"stu %@",stu);
};

2.6 使用枚举器

1
2
3
4
5
NSEnumerator * enumerator = [muDic objectEnumerator];
Student * tmp;
while (tmp = [enumerator nextObject]) {
NSLog(@"tmp %@",tmp);
}

新博客文章地址:NSDictionary字典创建,获取,遍历,可变字典的删除
CSDN文章地址:NSDictionary字典创建,获取,遍历,可变字典的删除

文章目录
  1. 1. 1 NSDictionary 字典
  2. 2. 1.1 创建字典,不可变的
  3. 3. 1.2 快捷创建方式
  4. 4. 1.3 字典中可以存任意数据类型
  5. 5. 1.4 获得字典的长度
  6. 6. 1.5 从字典中取值
  7. 7. 1.6 遍历
  8. 8. 2 NSMutableDictionary 可变字典
    1. 8.1. 2.1 创建一个可变长度字典
    2. 8.2. 2.2 向字典中存储数据
    3. 8.3. 2.3 删除
    4. 8.4. 2.4 全部删除
    5. 8.5. 2.5 使用for循环遍历字典
    6. 8.6. 2.6 使用枚举器