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, }
  
 

文章来源: chenyu.blog.csdn.net，作者：chen.yu，版权归原作者所有，如需转载，请联系作者。

原文链接：chenyu.blog.csdn.net/article/details/81124636