OBJECTIVE-C (Foundation framework One nsdictionary)

Nsdictionary

Immutable dictionaries

Ways to create a dictionary

        How to create a dictionary        nsdictionary *dy = [Nsdictionary dictionarywithobject:@ "a" forkey:@ "B"];        Nsdictionary *dy1 = [Nsdictionary dictionarywithobjectsandkeys:@ "a", @ "B", @ "C", @ "D", nil];                Quick Create dictionary        //duplicate key value, duplicate cannot save to dictionary        nsdictionary *dy2 = @{@ "we": @ "haha", @ "we": @ "Ha"};                NSLog (@ "%@", dy);        NSLog (@ "%@", dy1);        NSLog (@ "%@", Dy2);

Get the length of the dictionary

        //Get dictionary lengthNsdictionary *dy2 = @{@"We":@"haha",@"W":@"ha"}; NSLog (@"%lu", Dy2.count);//Output 2//if the key value is repeated, the length is not countedNsdictionary *dy2 = @{@"We":@"haha",@"We":@"ha"}; NSLog (@"%lu", Dy2.count);//Output 1

The traversal of a dictionary

Nsdictionary *dy1 = [Nsdictionary Dictionarywithobjectsandkeys:@"a",@"b",@"C",@"D", nil]; //quickly create a dictionary//Duplicate key value, duplicate cannot be saved to dictionaryNsdictionary *dy2 = @{@"We":@"haha",@"W":@"ha"}; NSLog (@"%lu", Dy2.count); //the traversal of a dictionary         for(NSString *keyinchdy2) {NSLog (@"key =%@, value =%@", Key, [Dy2 Objectforkey:key]); }        //Enumeration Type Traversal[Dy1 enumeratekeysandobjectsusingblock:^ (IDKeyIDobj, BOOL *stop) {NSLog (@"key =%@, value =%@", key, obj); }];

Save the dictionary in a file

        //Save the dictionary to a fileNsdictionary *dy2 = @{@"We":@"haha",@"W":@"ha"}; BOOL Iswrite= [Dy2 writetofile:@"/users/cloudwalk/desktop/test.plist"Atomically:yes]; if(iswrite) {NSLog (@"Write Success"); }

Reading a dictionary from a file

        Nsdictionary *readdy2 = [nsdictionary dictionarywithcontentsoffile:@ "/users/cloudwalk/desktop/ Test.plist"];        NSLog (@ "%@", readDy2);        

Build an array dictionary by adding arrays to the dictionary

Nsarray *sdarr = [Nsarray arraywithobjects:@"Zaozhuang",@"Jinan", nil]; Nsarray*jxarr = [Nsarray arraywithobjects:@"Jiujiang",@"Nanchang", nil]; Nsdictionary*citys = [Nsdictionary Dictionarywithobjectsandkeys:sdarr,@"SD", Jxarr,@"JX", nil]; NSLog (@"citys =%@", citys);

        Nsdictionary *citys = [Nsdictionary Dictionarywithobjectsandkeys:sdarr,@ "SD", Jxarr,  @ "jx", nil];        NSLog (@ "citys =%@", citys);         // Save the Citys in        a file [Citys writetofile:@ "/users/cloudwalk/desktop/test1.plist" Atomically:yes];

OBJECTIVE-C (Foundation framework One nsdictionary)