Store to-do items locally (improve on to-do items)

utilize UserDefault Store content in the system sandbox , adopt JSON Encoding and decoding realize the persistent storage of data , Every time you open the application, the operation will be saved to the local .

Find sandbox path

print(NSHomeDirectory())

use command+ Space copy path to find folder , open Library Folder , And on again Preferences Folder , Open the inside plist file , You can see the stored content , Click on Type You can see the basic type of storage .

 

  Because it is self-defined Todo type , So it can't be saved plist file , Need to transfer data type , use json code , however Todo The type must comply with the protocol of encoding and decoding .

 

func saveData(){
        // The local store 
        do{
          let data = try JSONEncoder().encode(todos)
            UserDefaults.standard.set(data, forKey: kTodosKey)// Because it is Todo Type cannot be saved plist file , Need to transfer data type , use json code 
        }catch{
            print(" Coding errors ")
        }
    }

 key Define for yourself

In the add, modify and delete function of the to-do list, call the storage function to code and store , stay ViewDidLoad（） Call the decoding function at the beginning to decode the read content .

if let data = UserDefaults.standard.data(forKey: kTodosKey){
            if let todos = try? JSONDecoder().decode([Todo].self, from: data){
                self.todos = todos
            }else{
                print(" Decoding failed ")
            }
        }// Take the data