OS&Swift-Realm(英語)の勉強

Installing RealmSwift

Open Terminal

cd to project directory

pod init (terminal/creates a Podfile)

open Podfile

write: pod 'RealmSwift' right before "end"

save

pod install (terminal)

go back to the project directory and open .xcworkspace file

Explanation
→ Realm is a local database. All of the data you create, store, retrieve are all stored locally on the device.
→ How it's all stored and managed is done in one file: Realm file
[ Realm Studio ] → allows you to browse data stored, add etc
—> need to open a Realm file
how to find the realm file?

add the following line in Xcode (under ViewController.swift → viewDidLoad())

print(Realm.Configuration.defaultConfiguration.fileURL)

Run the app (simulator)

A file directory will be there

open terminal

open///Users/kevin/Library/Developer/CoreSimulator/Devices/37688EE4-2343-4EA5-8C78-0BE25E8706D0/data/Containers/Data/Application/084E7DBC-723B-47E9-9267-CE5B81163075/Documents/default.realm

(ユーザーによってディレクトリが異なります)

Realm Studio will automatically open the file

Actually Using it

import RealmSwift

//make sure that any data or classes that you want to save into the realm
//file subclasses Object

class Cat: Object{

	//to save it into the realm folder, make sure to put
	//@objc dynamic -> these 2 keywords in front
	@objc dynamic var name: String?
	@objc dynamic var color: String?
	@objc dynamic var gender: String?
	
}

let realm = try! Realm()  //make a reference to the realm file

var myCat = Cat() //create new Cat object
myCat.name = "Moe"
myCat.gender = "Male"
myCat.color = "Orange"

//below is how to actually save the data to the realm file
//everytime you need to do something with the realm file, such as
//change, update, delete, etc, you need to realm.write { } (or realm.beginWrite())
try! realm.write{   //we put try! to ignore potential errors
	realm.add(myCat)
}

→ If you're gonna use realm.beginWrite(), you must try! realm.commitWrite() as well
Example:

@objc func didTapSaveButton(){
        
        if let text = textField.text, !text.isEmpty {
            
            let date = datePicker.date
            
            realm.beginWrite()
            
            let newItem = ToDoListItem()        //create new object
            newItem.date = date
            newItem.item = text
            realm.add(newItem)
            
            try! realm.commitWrite()
            
            completionHandler?()
            navigationController?.popToRootViewController(animated: true)
        }
        else{
            print("Add something")
        }
    }

Retrieving Data from Realm file example:

let results = realm.objects(Cat.self)  //returns an array

print(results[0].name)  //구조체이기 때문에 . 으로 접근

//"Moe"

Filter機能の例:

let results = realm.objects(Cat.self).filter("name = 'Moe'")

print(results.count)  //prints how many