Swift Dictionary Class

Provides a collection of dictionaries in the foundation framework that are composed of key-value pairs. The key collection cannot be duplicated, and the value collection has no special requirements. The elements in the keys and values collection can be any object, but cannot be nil. The Foundation Framework Dictionary class is also divided into nsdictionary immutable dictionaries and nsmutabledictionary mutable dictionaries.
First, Nsdictionary class

Nsdictionary has many methods and properties, and the following summarizes its common methods and properties.

Initwithdictionary: constructor that creates nsdictionary objects through Swift's dictionary.

Initwithobjects:forkeys: A constructor that creates a Nsdictionary object from a collection of keys and a collection of values.
The length of the Count dictionary collection.
Objectforkey: Gets the value object by key.
AllKeys: Returns all key collections.
Here's a sample code for the Nsdictionary array:

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2. Import Foundation
8. Let keystring: nsstring = "One, three four five" ①
10. var keys: Nsarray = keystring.componentsseparatedbystring ("") ②
16. Let valuestring: nsstring = "Alpha Bravo Charlie Delta echo" ③
18. var values: Nsarray = valuestring.componentsseparatedbystring ("") ④
24. Vardict: nsdictionary = nsdictionary (Objects:keys, forkeys:values) ⑤
30. NSLog ("%@", Dict.description) ⑥
36. varvalue:nsstring = Dict.objectforkey ("three") as Nsstring⑦
38. NSLog ("three =%@", value)
44. Varkys = Dict.allkeys⑧
46. For Item:anyobject in Kys {⑨
48. var key = item as NSString
50. NSLog ("%@-%@", Key, Dict.objectforkey (key) as NSString)
52. }

Line ① and line ③ of the above code are NSString strings, which consist of words and spaces. The ② line and the ④ line code use spaces to split the string, and the return type is the Nsarray array.
The ⑤ Line code instantiates the Nsdictionary object, and the objects parameter is the value array Values,forkeys parameter is. The ⑥ Line Code Description property is the content of the obtained dictionary. The ⑦ line code reads the value corresponding to the key by means of the Objectforkey method, and is converted to the NSString type.
Line ⑧ code Dict.allkeys is to get all the key collection Kys, the ⑨ line code is the traversal key collection Kys.
The output results are as follows:

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2. 2014-07-06 20:19:07.274 playgroundstub_osx[4110:303] {
4. five = echo;
6. four = Delta;
8. one = Alpha;
10. three = Charlie;
12. both = Bravo;
14. }
16. 2014-07-06 20:19:07.281 playgroundstub_osx[4110:303] three = Charlie
18. 2014-07-06 20:19:07.296 playgroundstub_osx[4110:303] One-alpha
20. 2014-07-06 20:19:07.300 playgroundstub_osx[4110:303] Five-echo
22. 2014-07-06 20:19:07.305 playgroundstub_osx[4110:303] Three-charlie
24. 2014-07-06 20:19:07.308 playgroundstub_osx[4110:303] Two-bravo
26. 2014-07-06 20:19:07.313 playgroundstub_osx[4110:303] Four-delta

Second, Nsmutabledictionary class
Nsmutabledictionary is a subclass of Nsdictionary, it has many methods and properties, and the following summarizes its commonly used methods and properties.
?-setobject:forkey: By key and value.
-removeobjectforkey: Removes the value by key.
Here's a sample code for the Nsdictionary array:

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2. Import Foundation
8. var mutable: nsmutabledictionary = nsmutabledictionary () ①
10. Add Objects
12. Mutable.setobject ("Tom", Forkey: "[email protected]") ②
14. Mutable.setobject ("Bob", Forkey: "[email protected]")
20. NSLog ("%@", mutable.description)
26. var keys = Mutable.allkeys
28. For item:anyobject in keys {
30. var key = item as NSString
32. NSLog ("%@-%@", Key, Mutable.objectforkey (key) as NSString)
34. }

The preceding code, line ①, is instantiated nsmutabledictionary, and the ② line of code is to add keys and values through the SetObject method.
The output results are as follows:

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1. 2014-07-06 20:42:11.596 playgroundstub_osx[4332:303] {
2. "[email protected]" = Bob;
3. "[email protected]" = Tom;
4. }
5. 2014-07-06 20:42:11.605 playgroundstub_osx[4332:303] [email protected]-Bob
6. 2014-07-06 20:42:11.608 playgroundstub_osx[4332:303] [email protected]–tom

Iii. the relationship between Nsdictionary and dictionary
The relationship between Nsdictionary and dictionary is like the relationship between Nsarray and array, and Swift can bridge them automatically at the bottom, and the result of a Nsdictionary object bridging is [nsobject: Anyobject] Dictionary (the value is NSObject type, the key is a dictionary dictionary of type Anyobject).
Let's look at an example that uses dictionary and nsdictionary:

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2. Import Foundation①
8. Let keystring: nsstring = "One of the three four five"
10. Let keys: Nsarray = keystring.componentsseparatedbystring ("")
16. Let valuestring: nsstring = "Alpha Bravo Charlie Delta echo"
18. Let values: Nsarray = valuestring.componentsseparatedbystring ("")
24. Let foundationdict: nsdictionary = nsdictionary (objects:values, Forkeys:keys) ②
30. Let swiftdict: Dictionary = Foundationdict③
32. println (swiftdict.description)
38. Let Value:anyobject? = swiftdict["three"]④
40. println ("three = \ (value)")
46. For (key, value) in Swiftdict {⑤
48. println ("\ (key)-\ (value)")
50. }

Code line ① is the introduction of foundation. The ② code declares and initializes the Nsdictionary dictionary, and the ③ line of code is to assign the Nsdictionary dictionary to the Dictionary dictionary, a process that also casts a type, not just nsdictionary to dictionary conversions, And their internal elements have also been transformed.

The ④ line code is the value of the three key from the dictionary dictionary, and its type is an optional anyobject type, because it is possible that this value cannot be taken. The ⑤ line of code is to traverse the dictionary dictionary key and Value collection.

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Swift Dictionary Class