IOS学习笔记二十一(NSDictionary、NSMutableDictionary)

1、NSDictionary、NSMutableDictionary

可以理解为java里面的map,一个key对应一个value，key不可以重复

NSDictionary不可变，NSMutableDictionary可变

NSMutableDictionary比NSDictionary多了一些增加，删除，修改的函数

比如setObject:forKey:  removeObjectForKey:

2、测试Demo

NSDictionary+print.h

#import <Foundation/Foundation.h>

#ifndef NSDictionary_print_h
#define NSDictionary_print_h
@interface NSDictionary (print)
-(void)print;
@end

#endif /* NSDictionary_print_h */

NSDictionary+print.m

#import <Foundation/Foundation.h>
#import "NSDictionary+print.h"

@implementation NSDictionary(print)
-(void)print
{
    NSMutableString *result = [NSMutableString stringWithFormat:@"{"];
    for (id key in self)
    {
        [result appendString:[key description]];
        [result appendString:@"="];
        [result appendString:[self[key] description]];
        [result appendString:@", "];
    }
    [result appendString:@"}"];
    NSLog(@"%@", result);
}
@end

main.m

#import "NSDictionary+print.h"

int main(int argc, char * argv[]) {
    @autoreleasepool {
        NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"chenyu1", @"1", @"chenyu2", @"2", @"chenyu3", @"3", @"chenyu4", @"4", @"chenyu5", @"5",nil];
        [dict print];
        NSLog(@"dict有%ld个key-value", [dict count]);
        NSLog(@"key is 2 value is %@", [dict[@"2"] description]);
        NSLog(@"key is 2 value is %@", [dict objectForKey:@"2"]);
        NSLog(@"dict 所有的key是:%@", [dict allKeys]);
        NSEnumerator *en = [dict objectEnumerator];
        id obj;
        //遍历value
        while (obj = [en nextObject])
        {
            NSLog(@"%@", obj);
        }
        [dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
            NSLog(@"key的值为:%@", key);
            NSLog(@"value的值为:%@", obj);
        }];

        NSMutableDictionary *muDict = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"chenyu1", @"1", @"chenyu2", @"2", @"chenyu3", @"3", @"chenyu4", @"4", @"chenyu5", @"5",nil];

        [muDict print];

        [muDict setObject:@"chen6" forKey:@"6"];
        [muDict setObject:@"chen6" forKey:@"3"];
        [muDict print];
        [muDict removeObjectForKey:@"1"];
        [muDict print];
  }
}

3、运行结果

2018-07-19 23:40:03.444261+0800 cyTest[67110:13778920] {3=chenyu3, 1=chenyu1, 4=chenyu4, 2=chenyu2, 5=chenyu5, }
2018-07-19 23:40:03.446141+0800 cyTest[67110:13778920] dict有5个key-value
2018-07-19 23:40:03.446320+0800 cyTest[67110:13778920] key is 2 value is chenyu2
2018-07-19 23:40:03.446681+0800 cyTest[67110:13778920] key is 2 value is chenyu2
2018-07-19 23:40:03.446972+0800 cyTest[67110:13778920] dict 所有的key是:(
    3,
    1,
    4,
    2,
    5
)
2018-07-19 23:40:03.447145+0800 cyTest[67110:13778920] chenyu3
2018-07-19 23:40:03.447340+0800 cyTest[67110:13778920] chenyu1
2018-07-19 23:40:03.447447+0800 cyTest[67110:13778920] chenyu4
2018-07-19 23:40:03.447578+0800 cyTest[67110:13778920] chenyu2
2018-07-19 23:40:03.447690+0800 cyTest[67110:13778920] chenyu5
2018-07-19 23:40:03.448208+0800 cyTest[67110:13778920] key的值为:3
2018-07-19 23:40:03.448322+0800 cyTest[67110:13778920] value的值为:chenyu3
2018-07-19 23:40:03.448422+0800 cyTest[67110:13778920] key的值为:1
2018-07-19 23:40:03.448515+0800 cyTest[67110:13778920] value的值为:chenyu1
2018-07-19 23:40:03.448613+0800 cyTest[67110:13778920] key的值为:4
2018-07-19 23:40:03.466511+0800 cyTest[67110:13778920] value的值为:chenyu4
2018-07-19 23:40:03.466823+0800 cyTest[67110:13778920] key的值为:2
2018-07-19 23:40:03.466983+0800 cyTest[67110:13778920] value的值为:chenyu2
2018-07-19 23:40:03.467161+0800 cyTest[67110:13778920] key的值为:5
2018-07-19 23:40:03.467334+0800 cyTest[67110:13778920] value的值为:chenyu5
2018-07-19 23:40:03.467602+0800 cyTest[67110:13778920] {3=chenyu3, 1=chenyu1, 4=chenyu4, 2=chenyu2, 5=chenyu5, }
2018-07-19 23:40:03.467838+0800 cyTest[67110:13778920] {3=chen6, 1=chenyu1, 6=chen6, 4=chenyu4, 2=chenyu2, 5=chenyu5, }
2018-07-19 23:40:03.468030+0800 cyTest[67110:13778920] {3=chen6, 6=chen6, 4=chenyu4, 2=chenyu2, 5=chenyu5, }