swift--Dictionary (dictionary)

1. Creation and initialization of dictionaries

2. Create an empty dictionary

3. Adding, modifying, and deleting data from a dictionary

4. Get value based on key

5. Convert value to a specific type

6. Enumerate the keys and value in the dictionary

7. Convert key and value to array

1 varemployee1:dictionary<string,string> = ["name":"Bill"," Company":"Microsoft"]2println (EMPLOYEE1)//[Company:microsoft,name:bill] sorted in alphabetical order. 3 4 varEmployee2 = ["name":"John"," Company":"Oracle"," Age": +]//without specifying a type, you can set it to another type, such as an integer5println (EMPLOYEE2);

1 varDict1 = ["Product_Name":"Ice Cream"," Price":5.5]2println (Dict1)//Price = "5.5; "Product_Name" = "ice cream", converts 5.5 into a string. If an integer is used, the output remains an integer. 3 4 varDict = Dictionary<int, string> ()//Create an empty dictionary5dict[ -]="Hello World"             //No 20 is filled, and 20 is modified. 6println (Dict)//[20:hello World]7 8Dict = [:]//empty array, key type is Int,value type is string9 Tendict[ +]="ABCD" Onedict[ -]="XYZ" Aprintln (Dict)//[20:XYZ,21:ABCD] -  - ifLet OldValue = Dict.updatevalue ("airplane ", forkey:21)//If there are 21 in the dictionary, the previous value is returned, and nil is returned if there is no 21. In the SWIFT statement, there is no parentheses after the IF.  the { -println"the old value is \ (oldValue)")//the old value is ABCD - } -println (Dict)//[20:xyz,21: Aircraft] +println (Dict.count)//2 -  +Let Age1:int = employee2[" Age"] asInt//Age is unexpected . Aprintln (AGE1);// + at  - ifLet Age2:int? = (employee2[" Age"] as? INT)//If this age does not exist, then nil will be returned, but int cannot save nil, so the post-add? //here output 32, if changed to employee2["Age1"], then return does not exist this key. - { - println (age2) - } - Else in { -println"This key does not exist in the dictionary")        to}

1dict[ -] = Nil//Delete a key in the dictionary directly, and the corresponding value is also deleted. Key and value always appear in pairs. 2println (Dict)//[21: Airplane] 20 has been deleted3 4Let OldValue = Dict.removevalueforkey ( +)//returns 21 for the corresponding value5println (OldValue)//Aircraft6 7 //enumerating keys and value in a dictionary8  for(Key, value)inchemployee19 {Tenprintln"\ (key): \ (value)");  One } A  -  forKeyinchEmployee1.keys - { the println (Key) - } -  -  forKeyinchEmployee2.keys//error, Employee2 is implicitly declared dict, so the keys will not be found + { - } + //Convert A  forKeyinch(Employee2 asDictionary). Keys at { - println (Key) - } -  -  forValueinchemployee1.values - { in println (value) - } todict[ A] ="ABC" +Let keys =Array (Dict.keys) -println (keys)//[] the  *Let values =Array (dict.values) $println (values)//[ABC]

swift--Dictionary (dictionary)