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valuewhile (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, }

 

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