configurePersistentStoreCoordinator not called for saveAs NSPersistentDocument

Question

I experience an odd behaviour regarding saving an NSPersistentDocument. I can create a new document which is autosaved without an issue. But when I save it write(to: ofTyp

Answer 1

Another, simpler workaround:

The following code has a bug. Please refer to the bug fixed version cited below.

extension NSPersistentStoreCoordinator {

  @objc func x_migratePersistentStore(_ store: NSPersistentStore, to URL: URL, options: [AnyHashable : Any]? = nil, withType storeType: String) throws -> NSPersistentStore {
    var opt: [AnyHashable : Any] = options ?? [:]

    if #available(OSX 10.13, *) {
      opt[NSBinaryStoreSecureDecodingClasses] = NSSet(array: [ NSColor.self ])
    }

    return try x_migratePersistentStore(store, to: URL, options: opt, withType: storeType)
  }

}

class Document: NSPersistentDocument {

  override init() {
    super.init()

    let s1 = #selector(NSPersistentStoreCoordinator.migratePersistentStore(_:to:options:withType:))
    let s2 = #selector(NSPersistentStoreCoordinator.x_migratePersistentStore(_:to:options:withType:))
    let m1 = class_getInstanceMethod(NSPersistentStoreCoordinator.self, s1)!
    let m2 = class_getInstanceMethod(NSPersistentStoreCoordinator.self, s2)!
    method_exchangeImplementations(m1, m2)
  }

  override func configurePersistentStoreCoordinator(for url: URL, ofType fileType: String, modelConfiguration configuration: String?, storeOptions: [String : Any]? = nil) throws {
    // keep yours
  }

}

Added:

This workaround is going to be a practical solution until they enhance NSPersistentDocument.write(to...) to take into account of options or they implement other means to handle options. Those options will be given to NSPersistentStoreCoordinator.migratePersistentStore(...) and then be used to instantiate NSPersistentStore.

Bug Fixed Version:

There was a bug in the preceding workaround. Opening document files, creating new files, making changes, waiting for thirty second to the document being auto-saved, closing them, and/or save-as-ing them randomly would cause the initial error. Reported by Wizard of Kneup.

Here is a fixed version using singleton to make sure swizzling is applied only once.

extension NSPersistentStoreCoordinator {

  @objc func x_migratePersistentStore(_ store: NSPersistentStore, to URL: URL, options: [AnyHashable : Any]? = nil, withType storeType: String) throws -> NSPersistentStore {
    var opt: [AnyHashable : Any] = options ?? [:]

    if #available(OSX 10.13, *) {
      opt[NSBinaryStoreSecureDecodingClasses] = NSSet(array: [ NSColor.self ])
    }

    return try x_migratePersistentStore(store, to: URL, options: opt, withType: storeType)
  }

  class MigratePersistentStoreInitializer {
    init() {
      let s1 = #selector(NSPersistentStoreCoordinator.migratePersistentStore(_:to:options:withType:))
      let s2 = #selector(NSPersistentStoreCoordinator.x_migratePersistentStore(_:to:options:withType:))
      let m1 = class_getInstanceMethod(NSPersistentStoreCoordinator.self, s1)!
      let m2 = class_getInstanceMethod(NSPersistentStoreCoordinator.self, s2)!
      method_exchangeImplementations(m1, m2)
    }

    static let singlton = MigratePersistentStoreInitializer()  // Lazy Stored Property
  }

}

class Document: NSPersistentDocument {

  override init() {
    super.init()
    let _ = NSPersistentStoreCoordinator.MigratePersistentStoreInitializer.singlton
  }

  override func configurePersistentStoreCoordinator(for url: URL, ofType fileType: String, modelConfiguration configuration: String?, storeOptions: [String : Any]? = nil) throws {
    // keep yours
  }

}

References:

• Lazy Stored Properties