OC -- Foundation -- dictionary

One 、 What is a dictionary

NSDictionary Used to save the array with mapping relationship .NSDictionary Two sets of values are stored in the set , One group is key, The other group is value. They can all be pointers of any type .
key Values are not allowed to be repeated .
key and value There is a one-to-one correspondence between them .
hold NSDictionary All in key Put together , They formed a NSSet aggregate （key Values have no order ,key and key Cannot be repeated between )

Two 、NSDictionary

1. establish

Class method dicotionary start , The example method takes init start

dictionary:	Create one that does not contain any key-value Of NSDictionary
dictionaryWithContentdOfFile:(initWithContentsOfFile:)	Read the contents of the specified file , Initialize with the specified file contents NSD ictionary. This file is usually composed of NSDictionary Output generated
dictionaryWithDictionary:(initWithDictionary:)	Use existing NSDictionary Contains key-value To initialize the NSDictionary object
dictionaryWithObject:forKey:	Using a single key-value To create NSDictionary object
dictionaryWithobjects:forKeys:(initWithObjects:forKeys:)	Use two NSArray Assign separately key,value Collections can be created to contain multiple key-value Of NSDictionary
dictionaryWithObjectsAndKeys:(initWIthObjectsAndKeys:)	according to value1,key1,value2,key2… The format passed in multiple key-value Yes

2. visit

• count： return NSDictionary It contains key-value logarithm
• allKeys: Return all contained key
• allKeysForObject: Returns the specified value Corresponding to all key
• allValues: Returns all... Contained in the dictionary value
• objectForKey: Used to get the specified in the dictionary key Of value
• objectForKeyedSubscript: It is allowed to obtain the specified by subscript key Corresponding value
• valueForKey: Get specified key It's the same as value
• keyEnumerator: Return to traverse all in the dictionary key Of NSEnumerator object
• objectEnumerator: Returns all... In the dictionary value Of NSEnumerator object
• enumerateKeysAndObjectsUsingBlock: Use the specified code block to iterate through all the in the collection key-value Yes
• enumerateKeysAndObjectsWithOptions:usingBlock: Use the specified code block to iterate through all the in the collection key-value Yes , It can be transmitted into a NSEnumerationOptions Parameters
• writeToFile:atomically: Write the contents of the dictionary to a file

user Class interface

#import<Foundation/Foundation.h>
@interface User:NSObject
@property(nonatomic,copy)NSString* name;
@property(nonatomic,copy)NSString* pass;
-(id)initWithName:(NSString*)aName
             pass:(NSString*)aPass;
-(void)say:(NSString*)content;

@end

user The realization of the class

#import "06022.h"
#import<Foundation/Foundation.h>
@implementation User
-(id)initWithName:(NSString*)name
            pass:(NSString*)pass{
    
    if(self=[super init]){
    
        self->_name=name;
        self->_pass=pass;
        
    }
    return self;
}
-(void)say:(NSString*)content{
    
    NSLog(@"%@ say ：%@",self.name,content);
}
-(BOOL)isEqual:(id)other{
    
    if(self==other){
    
        return YES;
    }
    if([other class]==User.class){
    
        User* target=(User*)other;
        return  [self.name isEqualToString:target.name]&&[self.pass isEqualToString:target.pass];
    }
    return NO;
}
-(NSString*)description{
    
    return [NSString stringWithFormat:@"<User[name=%@,pass=%@]>",self.name,self.pass];
}
@end

Class interface

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface NSDictionary(print)
-(void)print;
@end

NS_ASSUME_NONNULL_END

The realization of the class

#import "0602.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:@","];
        
    }
    NSUInteger len = [result length];
    [result deleteCharactersInRange:NSMakeRange(len-2,2)];
    [result appendString:@"}"];
    NSLog(@"%@",result);
}
@end

test ：

#import<Foundation/Foundation.h>
#import"0602.h"
#import"06022.h"
int main(int argc,char* argv[]){
    
    @autoreleasepool {
    
        NSDictionary* dict = [NSDictionary
                              dictionaryWithObjectsAndKeys:
                                  [[User alloc]initWithName:@"sun"
                                                       pass:@"123"],@"one",
                              [[User alloc]initWithName:@"bai"
                                                   pass:@"345"],@"two",
                              [[User alloc]initWithName:@"sun"
                                                   pass:@"123"],@"three",
                              [[User alloc]initWithName:@"tang"
                                                   pass:@"178"],@"four",
                              [[User alloc]initWithName:@"niu"
                                                   pass:@"155"],@"five",nil];
        [dict print];
        NSLog(@"dict contain %ld individual key-value Yes ",[dict count]);
        NSLog(@"dict All of the key by ：%@",[dict allKeys]);
        NSLog(@"<User[name=sun,pass=123]> For all key by ：%@",[dict allKeysForObject:[[User alloc]initWithName:@"sun" pass:@"123"]]);
        NSEnumerator* en=[dict objectEnumerator];
        id value;
        while(value=[en nextObject]){
    
            NSLog(@"%@",value);
        }
        [dict enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
    
            NSLog(@"key The value of is :%@",key);
            [value say:@" Nana "];
            
        }];
    }
}

3. Yes NSDictionary Of key Sort

keysSortedByValueUsingSelector: According to all return values key Sort , Sweet value This method of must return NSOrderedAscending,NSOrderedDescending,NSOrderedSame One of these three enumeration values .
keysSortedByValueUsingComparator: Use the specified code to traverse key-value Yes , And according to the results of the dictionary of all key sorted . The method must return NSOrderedAscending,NSOrderedDescending,NSOrderedSame One of these three enumeration values .
keysSortedByValueWithOptions:usingComparator: Use the specified code to traverse key-value Yes , And according to the results of the dictionary of all key sorted . It can be transmitted into a NSEnumerationOptions Parameters

The code of the interface part is the same as the above , Here is the test code

#import<Foundation/Foundation.h>
#import"0602.h"
#import"06022.h"
int main(int argc,char* argv[]){
    
    @autoreleasepool {
    
        NSDictionary* dict = @{
    @"one":@"nana",
                               @"two":@"nuonuo",
                               @"three":@"magic",
                               @"four":@"hailuo"};
        [dict print];
        NSArray* keyArr1 = [dict keysSortedByValueUsingSelector:@selector(compare:)];
        NSLog(@"%@",keyArr1);
        NSArray* keyArr2 = [dict keysSortedByValueUsingComparator:^(id value1,id value2) {
    
            if([value1 length]>[value2 length]){
    
                return NSOrderedDescending;
                
            }if([value1 length]<[value2 length]){
    
                return NSOrderedAscending;
            }
            return NSOrderedSame;
        }];
        NSLog(@"%@",keyArr2);
    }
}

give the result as follows ：

• First call value Of compare： Methods the sorting , String comparison size is directly based on character encoding
• Call the code block for all of the dictionary for the second time value Compare the size ,value The longer the corresponding string , The system thinks that value The bigger it is .

4. Yes NSDictionary Of key Filter

NSDictionary Provide for the right to NSDictionary All of the key filtering , After completion, it will meet the return filter conditions key form NSSet.

The interface part and implementation part are the same as above , Here is the test code ：

#import<Foundation/Foundation.h>
#import"0602.h"
#import"06022.h"
int main(int argc,char* argv[]){
    
    @autoreleasepool {
    
        NSDictionary* dict = @{
    
            @"nuonuo":[NSNumber numberWithInt:89],
            @"hailuo":[NSNumber numberWithInt:69],
            @"nana":[NSNumber numberWithInt:75],
            @"magic":[NSNumber numberWithInt:109]};
        [dict print];
        NSSet* keySet = [dict keysOfEntriesPassingTest:^(id key,id value,BOOL* stop){
    
            return (BOOL)([value intValue]>80);
        }];
        NSLog(@"%@",keySet);
    }
}

give the result as follows ：

3、 ... and 、 Custom type as key

Requirements that custom types need to meet ：

Correctly rewritten isEqual： and hash Method
Realized copyWithZone： Method , It is best to return an immutable copy of the object . It's for security reasons , When the program bar more key-value After the value is passed into the dictionary , For a dictionary ,key What is critical , Dictionaries need to be based on key To visit value.value It is equivalent to the index of dictionary elements . If key Variable value , And the program can modify the dictionary through other variables key, It may cause the index of the dictionary to be destroyed , The integrity of the dictionary is destroyed

Supplement to class implementation

- (id) copyWithZone: (NSZone*) zone {
    
    NSLog(@"start");
    FKUser* newUser = [[[self class] allocWithZone:zone] init];
    newUser->name = name;
    newUser->pass = pass;
    return newUser;
}

test ：

#import<Foundation/Foundation.h>
#import"0602.h"
#import"06022.h"
int main(int argc,char* argv[]){
    
    @autoreleasepool {
    
        User* u1=[[User alloc]initWithName:@"bai" pass:@"345"];
        NSDictionary* dict = @{
    
            [[User alloc]initWithName:@"sun" pass:@"123"]:@"one",u1:@"two",
            [[User alloc]initWithName:@"sun" pass:@"123"]:@"three",
            [[User alloc]initWithName:@"tang" pass:@"178"]:@"four",
            [[User alloc]initWithName:@"niu" pass:@"155"]:@"five"};
        u1.pass = nil;
        [dict print];
    }
}

Four 、NSMUtableDictionary

NSMUtableDictionary Inherited NSDictionary, Representing one key-value Variable NSDictionary aggregate .

#import <Foundation/Foundation.h>
#import "NSDictionary+print.h"
int main(int argc, char* argv[]) {
    
    @autoreleasepool {
    
        NSMutableDictionary* dict = [NSMutableDictionary
                                     dictionaryWithObjectsAndKeys:
                                     [NSNumber numberWithInt:89], @" Hey ",  nil];
        dict[@" Hey "] = [NSNumber numberWithInt:99];
        [dict print];
        NSLog(@"again");
        dict[@" Nana "] = [NSNumber numberWithInt:69];
        [dict print];
        NSDictionary* dict2 = [NSDictionary
                               dictionaryWithObjectsAndKeys:
                               [NSNumber numberWithInt:79], @" magical ",
                               [NSNumber numberWithInt:89], @"hai", nil];
        [dict addEntriesFromDictionary:dict2];
        [dict print];
        [dict removeObjectForKey:@" Hey "];
        [dict print];
    }
    return 0;
}