Make selectForProcessing async.

Frameworks/SyncDatabase/SyncDatabase.swift

@@ -10,6 +10,9 @@ import Foundation
 import RSCore
 import RSDatabase
 
+public typealias SyncStatusesResult = Result<Array<SyncStatus>, DatabaseError>
+public typealias SyncStatusesCompletionBlock = (SyncStatusesResult) -> Void
+
 public struct SyncDatabase {
 
 	private let syncStatusTable: SyncStatusTable
@@ -30,8 +33,8 @@ public struct SyncDatabase {
 		syncStatusTable.insertStatuses(statuses, completion: completion)
 	}
 	
-	public func selectForProcessing() throws -> [SyncStatus] {
-		return try syncStatusTable.selectForProcessing()
+	public func selectForProcessing(completion: @escaping SyncStatusesCompletionBlock) {
+		return syncStatusTable.selectForProcessing(completion)
 	}
 
 	public func selectPendingCount(completion: @escaping DatabaseIntCompletionBlock) {

Frameworks/SyncDatabase/SyncStatusTable.swift

@@ -20,11 +20,10 @@ struct SyncStatusTable: DatabaseTable {
 		self.queue = queue
 	}
 
-	func selectForProcessing() throws -> [SyncStatus] {
-		var statuses: Set<SyncStatus>? = nil
-		var error: DatabaseError?
-
-		queue.runInTransactionSync { databaseResult in
+	func selectForProcessing(_ completion: @escaping SyncStatusesCompletionBlock) {
+		queue.runInTransaction { databaseResult in
+			var statuses = Set<SyncStatus>()
+			var error: DatabaseError?
 
 			func makeDatabaseCall(_ database: FMDatabase) {
 				let updateSQL = "update syncStatus set selected = true"
@@ -42,12 +41,16 @@ struct SyncStatusTable: DatabaseTable {
 			case .failure(let databaseError):
 				error = databaseError
 			}
-		}
 
-		if let error = error {
-			throw(error)
+			DispatchQueue.main.async {
+				if let error = error {
+					completion(.failure(error))
+				}
+				else {
+					completion(.success(Array(statuses)))
+				}
+			}
 		}
-		return statuses != nil ? Array(statuses!) : [SyncStatus]()
 	}
 	
 	func selectPendingCount(_ completion: @escaping DatabaseIntCompletionBlock) {