22 Foundation框架之NSDictionary和NSMutableDictionary

22 Foundation框架之NSDictionary和NSMutableDictionary

Tags: Objective-C

NSDictionary也是一种集合，跟NSSet不一样的地方在于它是key-value键值对，可以通过key索引来添加或者删除value。在一个NSDictionary对象中，每一个key必须是唯一的，但是不同的key对应的value可以相同，用key-value共同判定一个NSDictionary对象中是佛有跟它相同的元素。

22.1 NSDictionary的使用

代码实例如下：

GKHUser.h

#import <Foundation/Foundation.h>

@interface GKHUser : NSObject
@property (nonatomic, copy) NSString* name;
@property (nonatomic, copy) NSString* pass;

- (id) initWithName:(NSString *)aName pass:(NSString *)aPass;
- (void) say:(NSString *)content;
- (NSComparisonResult) compare:(GKHUser *)aUser;
@end

GKHUser.m

#import "GKHUser.h"

@implementation GKHUser

//类的初始化
- (id) initWithName:(NSString *)aName pass:(NSString *)aPass {
if (self = [super init]) {
self.name = aName;
self.pass = aPass;
}
return self;
}

- (void) say:(NSString *)content {
NSLog(@"%@说：%@", self.name, content);
}

//重写继承自NSObject的isEqual:方法
- (BOOL) isEqual:(id)object {
if (self == object) {
return YES;
}
if ([object class] == [self class]) {
GKHUser *target = (GKHUser *) object;
return [self.name isEqualToString:target.name] && [self.pass isEqualToString:target.pass];

}
return NO;
}

//重写继承自NSObject的description方法
- (NSString *) description {
return [NSString stringWithFormat:@"<GKHUser[name=%@, pass=%@]>", self.name, self.pass];
}

//重写继承自NSObject的hash方法
- (NSInteger) hash {
NSLog(@"====hash====");
NSInteger nameHash = (self.name == nil ? 0 : [self.name hash]);
NSInteger passHash = (self.pass == nil ? 0 : [self.pass hash]);
return nameHash * 31 + passHash;
}

- (NSComparisonResult) compare:(GKHUser *)aUser {
if ([aUser.name isGreaterThan:self.name]) {
return NSOrderedDescending;
}
else if ([aUser.name isLessThan:self.name]) {
return NSOrderedAscending;
}
else {
return NSOrderedSame;
}
}
@end

NSDictionay+print.h

#import <Foundation/Foundation.h>

//定义一个NSDictionary的category，里面包含一个print所有key-value的方法
@interface NSDictionary (print)
- (void) print;
@end

NSDcitionary+print.m

#import "NSDictionary+print.h"

@implementation NSDictionary (print)

- (void) print {
NSMutableString *result = [NSMutableString stringWithString:@"{"];
for (id key in self) {
[result appendString:[key description]];
[result appendString:@"="];
[result appendString:[self[key] description]];
[result appendString:@", "];
}
NSInteger len = [result length];//获取字符串的长度
//去掉最后的,和空格
[result deleteCharactersInRange:NSMakeRange(len -2, 2)];
[result appendString:@"}"];
NSLog(@"%@", result);
}
@end

NSDictionaryTest.m

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

int main(int argc, const char * argv[]) {
@autoreleasepool {
//初始化一个NSDictionary,不同的key可以有相同的value，而key之间都必须不相同
NSDictionary *d = [NSDictionary dictionaryWithObjectsAndKeys:
[[GKHUser alloc]initWithName:@"sun" pass:@"123"], @"one",
[[GKHUser alloc]initWithName:@"bai" pass:@"234"], @"two",
[[GKHUser alloc]initWithName:@"sun" pass:@"123"], @"three",
[[GKHUser alloc]initWithName:@"li" pass:@"456"], @"four",
[[GKHUser alloc]initWithName:@"zhao" pass:@"567"], @"five",
nil];
NSDictionary *dict =[NSDictionary dictionaryWithDictionary:d];
//输出dict
[dict print];

//dict包含了多少个key-value对
NSLog(@"dict包含了%ld个key-value对", [dict count]);

//返回dict包含的所有keys
NSLog(@"dict包含的所有keys为：%@", [dict allKeys]);
//返回dict的某个对象值所对应的所有的keys
NSLog(@"dict中值为\"%@\"对应的所有keys为：%@", [[GKHUser alloc]initWithName:@"sun" pass:@"123"],
[dict allKeysForObject:[[GKHUser alloc]initWithName:@"sun" pass:@"123"]]);

//返回dict包含的所有values
NSLog(@"dict包含的所有values为：%@", [dict allValues]);
//返回dict中的某个key对应的value，使用vlueForKey:方法
NSLog(@"dict中key为\"four\"所对应的value为：%@", [dict valueForKey:@"four"]);
//返回dict中的某个key对应的value，使用objectForKey:方法
NSLog(@"dict中key为\"four\"所对应的value为：%@", [dict objectForKey:@"four"]);

//用NSDictionary的key枚举器枚举所有keys
NSEnumerator *keyEnumerator = [dict keyEnumerator];
id key;
while (key= [keyEnumerator nextObject]) {
NSLog(@"%@", key);
}
//用NSDictionary的value枚举器枚举所有values
NSEnumerator *valueEnmuerator = [dict objectEnumerator];
id value;
while (value = [valueEnmuerator nextObject]) {
NSLog(@"%@", value);
}
//使用Block函数对NSDictionary进行枚举
[dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
NSLog(@"key的值为%@", key);
[obj say:@"iOS编程"];
}];
NSLog(@"*****************************************");

//根据value输出key的排序，使用匿名comparator方法
NSArray *keyArr1 = [dict keysSortedByValueUsingComparator:^NSComparisonResult(id obj1, id obj2) {
if ([[obj1 name ]length] > [[obj2 name]length]) {
return NSOrderedDescending;
}
else if ([[obj1 name ]length] < [[obj2 name ]length]) {
return NSOrderedAscending;
}
else {
return NSOrderedSame;
}
}];
NSLog(@"%@", keyArr1);
//根据value输出key的排序，使用value自带的compare:方法做对比
NSArray *keyArr2 = [dict keysSortedByValueUsingSelector:@selector(compare:)];
NSLog(@"%@", keyArr2);
NSLog(@"*****************************************");

//根据value过滤满足条件的key
NSSet *keySet = [dict keysOfEntriesPassingTest:^BOOL(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
//返回value中name属性为sun的对应的key
return (BOOL)([[obj name] isEqualToString:@"sun"]);
}];
NSLog(@"%@", keySet);
}
return 0;
}

运行结果为：

{one=<GKHUser[name=sun, pass=123]>, five=<GKHUser[name=zhao, pass=567]>, three=<GKHUser[name=sun, pass=123]>, two=<GKHUser[name=bai, pass=234]>, four=<GKHUser[name=li, pass=456]>}
dict包含了5个key-value对
dict包含的所有keys为：(
one,
five,
three,
two,
four
)
dict中值为"<GKHUser[name=sun, pass=123]>"对应的所有keys为：(
one,
three
)
dict包含的所有values为：(
"<GKHUser[name=sun, pass=123]>",
"<GKHUser[name=zhao, pass=567]>",
"<GKHUser[name=sun, pass=123]>",
"<GKHUser[name=bai, pass=234]>",
"<GKHUser[name=li, pass=456]>"
)
dict中key为"four"所对应的value为：<GKHUser[name=li, pass=456]> dict中key为"four"所对应的value为：<GKHUser[name=li, pass=456]>
one
five
three
two
four
<GKHUser[name=sun, pass=123]>
<GKHUser[name=zhao, pass=567]>
<GKHUser[name=sun, pass=123]>
<GKHUser[name=bai, pass=234]>
<GKHUser[name=li, pass=456]>
key的值为one
sun说：iOS编程
key的值为five
zhao说：iOS编程
key的值为three
sun说：iOS编程
key的值为two
bai说：iOS编程
key的值为four
li说：iOS编程
*****************************************
(
four,
one,
three,
two,
five
)
(
five,
one,
three,
four,
two
)
*****************************************
{(
one,
three
)}

22.2 NSMutableDictionary的使用

代码示例如下：

NSMutableDictionary

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

int main(int argc, const char * argv[]) {
@autoreleasepool {
//创建一个NSMUtableDictionary字典，因为是可变的，可以先指定容量
NSMutableDictionary *dict =[NSMutableDictionary dictionaryWithCapacity:10];
NSDictionary *d = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:78], @"iOS编程",
[NSNumber numberWithInt:58], @"Java编程",
[NSNumber numberWithInt:68], @"PHP编程",
[NSNumber numberWithInt:38], @"C编程",
[NSNumber numberWithInt:28], @"Python编程",nil];

//把别的字典的实体都添加到NSMUtableDictionary
[dict addEntriesFromDictionary:d];

//用修改key对应的value，如果该key不存在，则添加该key-value
[dict setObject:[NSNumber numberWithInt:59]forKey:@"Java编程"];
dict[@"C++编程"] = [NSNumber numberWithInt:88];
NSLog(@"dict为%@：",dict);

//删除指定的value
[dict removeObjectForKey:@"PHP编程"];
//删除多个values
[dict removeObjectsForKeys:[NSArray arrayWithObjects:@"C编程",@"Java编程",nil]];
NSLog(@"dict为%@：",dict);
//删除所有values
[dict removeAllObjects];
NSLog(@"dict为%@：",dict);
}
return 0;
}

运行结果如下：

dict为{
"C++\U7f16\U7a0b" = 88;
"C\U7f16\U7a0b" = 38;
"Java\U7f16\U7a0b" = 59;
"PHP\U7f16\U7a0b" = 68;
"Python\U7f16\U7a0b" = 28;
"iOS\U7f16\U7a0b" = 78;
}
dict为{
"C++\U7f16\U7a0b" = 88;
"Python\U7f16\U7a0b" = 28;
"iOS\U7f16\U7a0b" = 78;
}
dict为{
}