Objective-c dictionary object, objective-c dictionary

Objective-c dictionary object, objective-c dictionary

The NSDictionary in oc serves the same purpose as the dictionary class in java and provides a combination of "key-value" pairs. For example, a dictionary class is used to store the Student name and student ID. The number is a key (unique) and the name is a value. Its methods include:

　　

 

The following uses an example to describe its usage:

1) Build a dictionary

　　

 1 #import <Foundation/Foundation.h> 2  3 int main(int argc , const char *argv[]){ 4     @autoreleasepool{ 5         NSDictionary *dicti1 = [NSDictionary     dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3", nil]; 6         NSEnumerator *keynum = [dicti1 keyEnumerator]; 7         for(NSString *key in keynum) 8             NSLog(@"key = %@ , value = %@",key,[dicti1 objectForKey:key]); 9         10         NSLog(@"----------------------------");11         NSDictionary *dicti2 = [[NSDictionary alloc]initWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3", nil];12         keynum = [dicti2 keyEnumerator];13         for(NSString *key in keynum)14             NSLog(@"key = %@ , value = %@",key,[dicti2 objectForKey:key]);15         16         NSLog(@"----------------------------");17         NSDictionary *dicti3 = @{@"1":@"zhangsan",@"2":@"lisi",@"3":@"wangwu"};18         keynum = [dicti3 keyEnumerator];19         for(NSString *key in keynum)20             NSLog(@"key = %@  , value = %@",key,[dicti3 objectForKey:key]);21         22         NSLog(@"------------------------------");23         NSArray *keyarray = @[@"1",@"2",@"3"];24         NSArray *valuearray = @[@"zhangsan",@"lisi",@"wangwu"];25         NSDictionary *dicti4 = [NSDictionary dictionaryWithObjects:valuearray forKeys:keyarray];26         keynum = [dicti4 keyEnumerator];27         for(NSString *key in keynum)28             NSLog(@"key = %@ , value = %@",key,[dicti4 objectForKey:key]);29         30     }31     return 0;32 }

2) dictionary Traversal

　　

 1 #import <Foundation/Foundation.h> 2  3 int main(int argc , const char *argv[]){ 4     @autoreleasepool { 5         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3", nil]; 6         NSEnumerator *number = [dicti keyEnumerator]; 7         for(NSString *key in number) 8             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]); 9         10         NSLog(@"----------------------------");11         NSArray *keyarray = [dicti allKeys];12         for(NSString *key in keyarray)13             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);14         15         NSLog(@"-----------------------------");16         for(NSString *key in  dicti)17             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);18         19         NSLog(@"-----------------------------");20         [dicti enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {21             NSLog(@"key = %@  ,value = %@",key,obj);22         }];23     }
　　　　return 0;24 }

3) File Reading

 1 #import <Foundation/Foundation.h> 2  3 int main(int argc , const char *argv[]){ 4     @autoreleasepool { 5         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangnwu",@"3",nil]; 6          7         NSString *filename = @"dicti.txt"; 8         BOOL iswrite = [dicti writeToFile:filename atomically:YES]; 9         if(iswrite)10             NSLog(@"write to file ok");11         else12             NSLog(@"write to file error");13         14         NSDictionary *dicti2 = [NSDictionary dictionaryWithContentsOfFile:filename];15         NSLog(@"dicti2 = %@",dicti2);16         17     }
　　　　return 0;18 }

4) Search

　　

1 # import <Foundation/Foundation. h> 2 3 int main (int argc, const char * argv []) 4 {5 @ autoreleasepool {6 NSDictionary * dicti = [NSDictionary dictionaryWithObjectsAndKeys: @ "zhangsan ", @ "1", @ "lisi", @ "2", @ "wangwu", @ "3", @ "zhangsan", @ "4", nil]; 7 8 NSArray * keyarray = [dicti allKeys]; // search for all key values 9 NSLog (@ "% @", keyarray); 10 11 NSArray * valuearray = [dicti allValues]; // query all values 12 NSLog (@ "% @", valuearray); 13 14 NSString * value = [dicti objectForKey: @ "1"]; // search for 15 NSLog (@ "value = % @", value); 16 17 value = dicti [@ "2"]; 18 NSLog (@ "value = % @", value); 19 20 NSArray * keyarray2 = @ [@ "1", @ "2", @ "3"]; // search for 21 NSArray * vlauearray2 = [dicti objectsForKeys: keyarray2 notFoundMarker: @ "nil"]; 22 NSLog (@ "vlauearray2 = % @", vlauearray2 ); 23 24 NSArray * keyarray3 = [dicti allKeysForObject: @ "zhangsan"]; 25 NSLog (@ "keyarray3 = % @", keyarray3); 26 27 NSDictionary * dicti2 = [dicti keywords: keyarray2]; 28 NSLog (@ "dicti2 = % @", dicti2); 29} 30 return 0; 31}

5) sort

　　

 1 #import <Foundation/Foundation.h> 2  3  4 int main(int argc,char **argv){ 5     @autoreleasepool { 6         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"2",@"lisi",@"3",@"wangwu",@"1",@"zhangsan",@"4",nil]; 7         NSLog(@"dicti = %@",dicti); 8          9         NSDictionary *dicti2 = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@1,@"lisi",@2,@"wangu",@3, nil];10         NSLog(@"dicti2 = %@",dicti2);11         12         NSArray *array = [dicti2 keysSortedByValueUsingSelector:@selector(compare:)];13         for(NSNumber *key in array)14             NSLog(@"key = %@,value = %@",key,dicti2[key]);15     }16     return 0;17 }

2. A variable Dictionary (NSDictionary) exists in the same dictionary object. Here we will illustrate its usage through an example:

　　

 

Code example:

　　

1 # import <Foundation/Foundation. h> 2 3 4 int main (int argc, char ** argv) {5 @ autoreleasepool {6 NSMutableDictionary * mdicti = [NSMutableDictionary Syntax: @ "zhangsan", @ "1 ", @ "lisi", @ "2", @ "wangwu", @ "3", nil]; 7 8 [mdicti setValue: @ "zhaoliu" forKey: @ "4"]; // if the key does not exist, add it. If the key exists, modify 9 NSLog (@ "mdicti = % @", mdicti); 10 11 [mdicti setValue: @ "zzz" forKey: @ "1"]; 12 NSLog (@ "mdicti = % @", mdicti ); 13 14 mdicti [@ "5"] = @ "bbb"; 15 NSLog (@ "mdicti = % @", mdicti); 16 17 NSDictionary * dicti = [NSDictionary dictionaryWithObjectsAndKeys: @ "aaa", @ "11", @ "bbb", @ "12", @ "ccc", @ "13", nil]; 18 [mdicti addEntriesFromDictionary: dicti]; 19 NSLog (@ "dicti = % @", mdicti); 20 21 [mdicti removeObjectForKey: @ "1"]; // Delete 22 NSLog (@ "mdicti = % @", mdicti); 23 24 NSArray * array = @ [@ "11", @ "12 ", @ "13"]; 25 [mdicti removeObjectsForKeys: array]; 26 NSLog (@ "mdicti = % @", mdicti); 27 28 [mdicti removeAllObjects]; // delete all 29 nslogs (@ "% @", mdicti); 30} 31 return 0; 32}