App 的核心是內容.那內容都有哪些方式存儲呢？
我們知道在iOS中存儲數據一般會用以下四種方式:
- NSKeyedArchiver：采用歸檔的形式來保存數據，一般NSString、NSDictionary、NSArray、NSData、NSNumber等類型，可以直接用NSKeyedArchiver進行歸檔和恢復.
- NSUserDefaults: 用來存儲配置信息 特點是簡單方便.通過[NSUserDefaults standardUserDefaults]獲取實例來存儲簡單的數據。
- 數據庫(Sqlite,Coredata)。存儲大量的信息
- 文件存儲：各種文件存儲。通過沙盒來進行存儲。
那Apple watch 端可以通過什么方式來存儲呢？
WX20170901-093638@2x.png
- plist
NSUserDefaults是快速共享信息的途徑。它適合存儲各種快速訪問和計算的小型數據，比如用戶名與檔案信息。存儲在Watch Extension中.
需要注意的是實現數據共享時候
你需要設定App Group來讓設備通過共享容器來實現數據共享，確保手表擴展和ios target都已如此設置。基本上就是針對兩個設備創建一個統一的App Group標識符，如下圖所示：APP Groups 標識符為group.com.db.iwatch
let defaults=NSUserDefaults(suiteName:
"group.com.db.iwatch")
watch extension端和 ios phone端就可以實現數據共享啦
- coredata
watchos2 之后開始支持coredata啦。在watch 端怎么實現coredata 存儲以及CRDU呢？
需要注意的是實現數據共享時候
APP Groups 標識符為group.com.db.iwatch
要了解coredata，就必須理解下面四個類所代表的意思，下面分別介紹：
- NSManagedObjectModel
代表了數據模型，也就是Xcode中創建的.xcdatamodel文件中所表訴的信息 - NSPersistentStore
是數據存放的地方，可以是SQLite、XML（僅OS X）、二進制文件、或僅內存中 - NSPersistentStoreCoordinator
是協調者，用來在NSManagedObjectContext和NSPersistentStore之間建立連接。 - NSManagedObjectContext
是應用程序唯一需要訪問的類，其中提供了對數據操作的一系列接口。 - NSManagedObject
是具體某個Table 對應的實體對象
通過上面簡單的描述來寫下面Watch端關于
首先初始化新建一個WatchCoreDataProxy.swift文件，通過該類來操作數據庫。
public class WatchCoreDataProxy: NSObject {
let sharedAppGroup:String = "group.com.db.iwatch"
//初始化單例該類
public class var sharedInstance : WatchCoreDataProxy {
struct Static {
static let instance : WatchCoreDataProxy = WatchCoreDataProxy()
}
return Static.instance
}
// MARK: - Core Data stack
public lazy var applicationDocumentsDirectory: URL = {
// The directory the application uses to store the Core Data store file. This code uses a directory named "com.makeandbuild.ActivityBuilder" in the application's documents Application Support directory.
let urls = FileManager.default.urls(for: .documentDirectory, in:.userDomainMask )
return urls[urls.count-1]
}()
//
public lazy var managedObjectModel: NSManagedObjectModel = {
// let proxyBundle = Bundle(identifier: "com.db.iwatch.WatchCoreDataProxy")
//注意此處是Model名稱，xcdatamodel對應的位置
let modelURL = Bundle.main.url(forResource: "Model", withExtension: "momd")
//let proxyBundle = Bundle(identifier: "com.makeandbuild.WatchCoreDataProxy")
// The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
//let modelURL = proxyBundle?.url(forResource: "Model", withExtension: "momd")
return NSManagedObjectModel(contentsOf: modelURL!)!
}()
public lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
//注意這里的shareAppGroup
var sharedContainerURL: URL? = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: self.sharedAppGroup) as URL?
if let sharedContainerURL = sharedContainerURL {
let storeURL = sharedContainerURL.appendingPathComponent("Model.sqlite")
print("the database mode url is:\(storeURL)")
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
do {
try coordinator!.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeURL, options: nil)
} catch {
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
dict[NSLocalizedFailureReasonErrorKey] = "There was an error creating or loading the application's saved data." as AnyObject?
dict[NSUnderlyingErrorKey] = error as NSError
let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
abort()
}
return coordinator
}
return nil
}()
//mangedObjectContext范問數據庫的句柄
public lazy var managedObjectContext: NSManagedObjectContext? = {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
let coordinator = self.persistentStoreCoordinator
if coordinator == nil {
return nil
}
var managedObjectContext = NSManagedObjectContext()
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
// MARK: - Core Data Saving support
//保存數據庫Context
public func saveContext () {
let context = self.managedObjectContext!
if (context.hasChanges) {
do {
try
context.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}
}
下面在coredata數據庫中添加Songs Table
coredata@2x.png
然后通過Editor 按鈕 Create NSManagerObject SubClass 產生如下類
extension Songs {
@nonobjc public class func fetchRequest() -> NSFetchRequest<Songs> {
return NSFetchRequest<Songs>(entityName: "Songs");
}
@NSManaged public var albumId: String?
@NSManaged public var coverUrl: String?
@NSManaged public var createTime: String?
@NSManaged public var duration: String?
@NSManaged public var favorite: Int16
@NSManaged public var name: String?
@NSManaged public var songId: String?
@NSManaged public var sourceUrl: String?
@NSManaged public var artist: String?
}
創建添加一條記錄到Song字段中去
public func createSong(songTmp:SongsModel){
let song:Songs = NSEntityDescription.insertNewObject(forEntityName: SongManager.SONG_DATABASE, into: DataBaseManager.getContext()) as! Songs
print("will insert songMode :\(songTmp)")
song.albumId = songTmp.albumId
song.name=songTmp.songName
song.songId=songTmp.songId
song.duration=songTmp.duration
song.artist=songTmp.atrtisName
song.coverUrl=songTmp.coverUrl
song.favorite=Int16(songTmp.favorite!)!
song.sourceUrl=songTmp.sourceUrl
let time = Date().timeIntervalSince1970
song.createTime = String.init(format: "%lld", time)
print("the name is:\(song.name)")
//對數據進行存儲.
DataBaseManager.saveManagedContext()
}
查詢所有歌曲如下圖所示：
public func fetchAllSongs(sortKey:String = "createTime")->[Songs]{
let fetchRequest = NSFetchRequest<Songs>(entityName: SongManager.SONG_DATABASE)
let sortDescriptor = NSSortDescriptor(key: sortKey, ascending: true)
fetchRequest.sortDescriptors=[sortDescriptor]
var fetchedSongs:[Songs]=[]
do {
fetchedSongs = try DataBaseManager.getContext().fetch(fetchRequest)
} catch{
print("Failed to fetch employees: \(error)")
}
return fetchedSongs
}
總結：
WatchOS可以通過coredata來存儲復雜的數據，plist來存儲較為簡單的數據，要實現app與watch 共享數據需要注意添加APP Groups 標識符.
