NSDictionary字典创建,获取,遍历,可变字典的删除 - iOS

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1 NSDictionary 字典

1.1 创建字典,不可变的

NSDictionary * dic = [NSDictionary dictionaryWithObjectsAndKeys:@"xiaozhe",@"name", nil];
NSLog(@"dic %@",dic);

2016-08-14 14:44:17.460 07-字典类[2325:547877] dic {
    name = xiaozhe;
1.2 快捷创建方式

NSDictionary * dic2 = @{ @"one":@"1",@"two":@"2"};
NSLog(@"dic2 %@",dic2);
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
NSArray * array = @[@"one",@"two"];
NSDictionary * dic3 = @{
                        @"one":@"1",
                        @"num":[NSNumber numberWithInt:10],
                        @"aaa":dic2,
                        @"bbb":dic,
                        @"ar1":array
NSLog(@"dic3 %@",dic3);
016-08-14 14:44:17.461 07-字典类[2325:547877] dic3 {
    aaa =     {
        one = 1;
        two = 2;
    ar1 =     (
    bbb =     {
        name = xiaozhe;
    num = 10;
    one = 1;

NSLog(@"count %ld",dic3.count);
1.5 从字典中取值

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
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);
NSEnumerator * enumerator =  [dic3 objectEnumerator];
id value;
while (value = [enumerator nextObject]) {
    NSLog(@"value %@",value);

2.1 创建一个可变长度字典

NSMutableDictionary * muDic = [[NSMutableDictionary alloc] initWithCapacity:0];
2.2 向字典中存储数据

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

[muDic removeObjectForKey:@"one"];
2.4 全部删除

[muDic removeAllObjects];
给一个 Student 类
@interface Student : NSObject
@property (nonatomic,assign) int age;
@property (nonatomic,strong) NSString * name;
- (id)initWithName:(NSString *)name andAge:(int)age;
@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];
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"];

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);

NSEnumerator * enumerator = [muDic objectEnumerator];
Student * tmp;
while (tmp = [enumerator nextObject]) {
    NSLog(@"tmp %@",tmp);
2.6 使用枚举器2.5 使用for循环遍历字典2 NSMutableDictionary 可变字典1.4 获得字典的长度