- New activity tracking subsystem

	- OCActivityManager
		- keeps track of activities
		- coalesces updates for maximum performance
		- relays activity information to main thread
	- OCActivity
		- describes an activity with description, status message, progress
		- provides cancel option
		- can contain an OCIssue for error resolution
	- OCActivityUpdate
		- encapsulates activity update information
		- allows publishing and unpublishing activities
		- allows update of individual activity properties
	- simplified creation of OCActivity objects and updates via the OCActivitySource protocol
- OCConnection
	- trying to upload a non-existant file now results in an error
	- extended internal error checks in uploadFileFromURL:
- OCCore+ItemList
	- experimental supply of activity information for background updates
- OCCore+LocalImport
	- addition of a import transformations
	- used by the FileProvider to transform select bundle document formats into ZIP archives on the fly
- OCSyncRecord
	- adding OCActivitySource conformance

ownCloudSDK/Activity/OCActivity.h

@@ -0,0 +1,89 @@
+//
+//  OCActivity.h
+//  ownCloudSDK
+//
+//  Created by Felix Schwarz on 24.01.19.
+//  Copyright © 2019 ownCloud GmbH. All rights reserved.
+//
+
+/*
+ * Copyright (C) 2019, ownCloud GmbH.
+ *
+ * This code is covered by the GNU Public License Version 3.
+ *
+ * For distribution utilizing Apple mechanisms please see https://owncloud.org/contribute/iOS-license-exception/
+ * You should have received a copy of this license along with this program. If not, see <http://www.gnu.org/licenses/gpl-3.0.en.html>.
+ *
+ */
+
+#import <Foundation/Foundation.h>
+#import "OCIssue.h"
+
+typedef NSString* OCActivityIdentifier;
+
+typedef NS_ENUM(NSUInteger, OCActivityState)
+{
+	OCActivityStatePending,	//!< Activity is pending
+	OCActivityStateRunning, //!< Activity is being executed
+	OCActivityStatePaused,  //!< Activity is paused
+	OCActivityStateFailed	//!< Activity has failed (and optionally awaits resolution)
+};
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class OCActivity;
+@class OCActivityUpdate;
+
+@protocol OCActivitySource
+
+@required
+@property(readonly,nonatomic) OCActivityIdentifier activityIdentifier; //!< Returns an identifier uniquely identifying the source's activity.
+
+@optional
+- (OCActivity *)provideActivity; //!< Returns a new instance of OCActivity representing the source's activity.
+
+@end
+
+@interface OCActivity : NSObject
+{
+	OCActivityIdentifier _identifier;
+
+	OCActivityState _state;
+
+	NSInteger _ranking;
+
+	NSString *_localizedDescription;
+	NSString *_localizedStatusMessage;
+
+	NSProgress *_progress;
+
+	OCIssue *_issue;
+
+	BOOL _isCancellable;
+}
+
+@property(strong) OCActivityIdentifier identifier; //!< Identifier uniquely identifying an activity
+
+@property(assign,nonatomic) OCActivityState state; //!< State of the activity
+
+@property(assign) NSInteger ranking; //!< Lower numbers for higher prioritized items
+
+@property(strong) NSString *localizedDescription; //!< Localized description of the activity (f.ex. "Copying party.jpg to Photos..")
+@property(nullable,strong) NSString *localizedStatusMessage; //!< Localized message describing the status of the activity (f.ex. "Waiting for response..")
+
+@property(nullable,strong) NSProgress *progress; //!< Progress information on the activity
+
+@property(nullable,strong) OCIssue *issue; //!< If .state is failed, an issue that can be used to resolve the failure (optional)
+
+@property(assign) BOOL isCancellable; //!< If YES, the activity can be cancelled
+
++ (instancetype)withIdentifier:(OCActivityIdentifier)identifier description:(NSString *)description statusMessage:(nullable NSString *)statusMessage ranking:(NSInteger)ranking;
+
+- (NSError *)applyUpdate:(OCActivityUpdate *)update; //!< Applies an update to the activity. Returns nil if the update could be applied, an error otherwise.
+- (NSError *)applyValue:(nullable id <NSObject>)value forKeyPath:(NSString *)keyPath; //!< Applies a new value to a keypath (entrypoint for subclassing)
+
+- (void)cancel;
+
+@end
+
+NS_ASSUME_NONNULL_END

ownCloudSDK/Activity/OCActivity.m

@@ -0,0 +1,93 @@
+//
+//  OCActivity.m
+//  ownCloudSDK
+//
+//  Created by Felix Schwarz on 24.01.19.
+//  Copyright © 2019 ownCloud GmbH. All rights reserved.
+//
+
+/*
+ * Copyright (C) 2019, ownCloud GmbH.
+ *
+ * This code is covered by the GNU Public License Version 3.
+ *
+ * For distribution utilizing Apple mechanisms please see https://owncloud.org/contribute/iOS-license-exception/
+ * You should have received a copy of this license along with this program. If not, see <http://www.gnu.org/licenses/gpl-3.0.en.html>.
+ *
+ */
+
+#import "OCActivity.h"
+#import "OCActivityUpdate.h"
+#import "NSError+OCError.h"
+
+@implementation OCActivity
+
+@synthesize identifier = _identifier;
+
+@synthesize ranking = _ranking;
+
+@synthesize localizedDescription = _localizedDescription;
+@synthesize localizedStatusMessage = _localizedStatusMessage;
+
+@synthesize progress = _progress;
+
+@synthesize issue = _issue;
+
+@synthesize isCancellable = _isCancellable;
+
++ (instancetype)withIdentifier:(OCActivityIdentifier)identifier description:(NSString *)description statusMessage:(nullable NSString *)statusMessage ranking:(NSInteger)ranking
+{
+	OCActivity *activity = [OCActivity new];
+
+	activity.identifier = identifier;
+	activity.localizedDescription = description;
+	activity.localizedStatusMessage = statusMessage;
+	activity.ranking = ranking;
+
+	return (activity);
+}
+
+- (void)cancel
+{
+	if (_isCancellable)
+	{
+		[self.progress cancel];
+	}
+}
+
+- (NSError *)applyUpdate:(OCActivityUpdate *)update
+{
+	__block NSError *error = nil;
+
+	if (update.type != OCActivityUpdateTypeProperty)
+	{
+		return (OCError(OCErrorInsufficientParameters));
+	}
+
+	[update.updatesByKeyPath enumerateKeysAndObjectsUsingBlock:^(NSString * _Nonnull keyPath, id<NSObject>  _Nonnull value, BOOL * _Nonnull stop) {
+		NSError *applicationError = nil;
+
+		if ([value isEqual:[NSNull null]])
+		{
+			value = nil;
+		}
+
+		if ((applicationError = [self applyValue:value forKeyPath:keyPath]) != nil)
+		{
+			error = applicationError;
+			*stop = YES;
+		}
+	}];
+
+	return (error);
+}
+
+- (NSError *)applyValue:(nullable id <NSObject>)value forKeyPath:(NSString *)keyPath
+{
+	// Entrypoint for subclassing
+	[self setValue:value forKeyPath:keyPath];
+
+	return (nil);
+}
+
+@end

ownCloudSDK/Activity/OCActivityManager.h

@@ -0,0 +1,47 @@
+//
+//  OCActivityManager.h
+//  ownCloudSDK
+//
+//  Created by Felix Schwarz on 25.01.19.
+//  Copyright © 2019 ownCloud GmbH. All rights reserved.
+//
+
+/*
+ * Copyright (C) 2019, ownCloud GmbH.
+ *
+ * This code is covered by the GNU Public License Version 3.
+ *
+ * For distribution utilizing Apple mechanisms please see https://owncloud.org/contribute/iOS-license-exception/
+ * You should have received a copy of this license along with this program. If not, see <http://www.gnu.org/licenses/gpl-3.0.en.html>.
+ *
+ */
+
+#import <Foundation/Foundation.h>
+#import "OCActivity.h"
+#import "OCLogTag.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface OCActivityManager : NSObject <OCLogTagging>
+
+#pragma mark - Init
+- (instancetype)initWithUpdateNotificationName:(NSString *)updateNotificationName;
+
+#pragma mark - Update notifications
+@property(readonly,nonatomic) NSNotificationName activityUpdateNotificationName;
+
+#pragma mark - Access
+@property(readonly,nonatomic) NSArray <OCActivity *> *activities;
+- (nullable OCActivity *)activityForIdentifier:(OCActivityIdentifier)activityIdentifier;
+
+#pragma mark - Updating
+- (void)update:(OCActivityUpdate *)update;
+
+@end
+
+extern NSString *OCActivityManagerNotificationUserInfoUpdatesKey; 	  //!< UserInfo key that contains an array of dictionaries providing info on the activity updates:
+
+extern NSString *OCActivityManagerUpdateTypeKey; 	//!< the type of the update [OCActivityUpdateType]
+extern NSString *OCActivityManagerUpdateActivityKey; 	//!< the updated activity object [OCActivity]
+
+NS_ASSUME_NONNULL_END