The Dictionary of Objective-c

1 // Dictionary: (keyword value)
 2 // NSArray * array = [NSArray array]; // empty array
 3 // NSDictionary * dictionary = [NSDictionary dictionary]; // empty dictionary
 4 NSDictionary * my = [NSDictionary dictionaryWithObject: @ "objective" forKey: @ "key"];
 5 NSLog (@ "% @", my);
 6 NSDictionary * to = [NSDictionary dictionaryWithObjectsAndKeys: @ "123", @ "abc", @ "456", @ "efg", nil]; // Create a dictionary containing multiple values
 7 NSLog (@ "% @", to);
 8 NSDictionary * me = @ {
 9 @ "a": @ "1",
10 @ "b": @ "2"
11};
12 NSLog (@ "% @,% li", me, me.count);
13 NSString * s = [me objectForKey: @ "a"]; // The object corresponding to the key value
14 NSString * ss = me [@ "b"]; // Almost like an array
15 NSLog (@ "% @,% @", ss, s);
16
17 // NSArray * keyArr = [me allKeys];
18 // for (NSString * key in keyArr)
19 // {
20 // NSLog (@ "% @ =% @", key, me [key]);
twenty one //        }
twenty two       
23 NSDictionary * niubi = [NSDictionary dictionaryWithObjectsAndKeys: @ "liyuanfang", @ "direnjie", @ "Moran", @ "fuermosi", @ "kenanfushou", @ "kenan", nil]; // Create a multiple dictionary
24 NSArray * keyArr = [niubi allKeys]; // Get all key values in the dictionary
25 for (NSString * key in keyArr)
26 {
27 NSLog (@ "% @ 问% @ What do you think about this?", Key, niubi [key]);
28}
29 / ************************************************ ********************************** /
30 // Retrieve all values from the dictionary
31 NSArray * valueArr = [me allValues];
32 NSLog (@ "take the value corresponding to all keys in the dictionary% @", valueArr);
33
34 // Since the dictionary exists, the developer must think of using it conveniently
35 // However, there are methods that can fetch keys or values independently: allKeys and allValues
36 // Because they are array attributes, they need to be placed in the newly created array object
37
38 // An effective method for traversal in OC language in enumerator,
39 // When applying, generally get the enumerator through ..... Enumerator and store it in its corresponding type NSEnumerator object
40 // This object will have a method called nextObject
41 // First get the enumerator of the key in the dictionary, then traverse the enumerator and get the value corresponding to the key
42 NSEnumerator * e = [me keyEnumerator];
43 id obj;
44 while (obj = [e nextObject]) {
45 NSLog (@ "% @ =% @", obj, me [obj]);
46}
47
48 // Get the enumerator corresponding to value
49 NSEnumerator * a = [me objectEnumerator];
50 while (obj = [a nextObject])
51 {
52 NSLog (@ "% @", obj);
53}
54
55 // Key and object enumeration block, stop stands for traversal stop
56
57 [me enumerateKeysAndObjectsUsingBlock: ^ (id key, id obj, BOOL * stop) {
58
59 NSLog (@ "key =% @, value =% @", key, obj);
60}]; 

The Dictionary of Objective-c