XDocumentSource File Provider Service

XDocumentSource.h

//
//  XDocumentSource.h
//  Textastic Universal
//
//  Created by Alexander Blach on 01.05.18.
//

#import <Foundation/Foundation.h>

@protocol XDocumentSourceProtocol
- (void)writeExtendedAttribute;
- (void)writeExtendedAttributeWithCompletionHandler:(void (^)(BOOL didWrite))completionHandler;
@end

@interface NSURL (XDocumentSource)
- (void)requestXDocumentSourceServiceWithCompletionHandler:(void (^)(NSURL *url))completionHandler;
@end

XDocumentSource.m

//
//  XDocumentSource.m
//  Textastic Universal
//
//  Created by Alexander Blach on 01.05.18.
//

#import "XDocumentSource.h"

@implementation NSURL (XDocumentSource)

// the completion handler is always called on the main queue
// you need to call -[NSURL startAccessingSecurityScopedResource] on the url before calling this method
- (void)requestXDocumentSourceServiceWithCompletionHandler:(void (^)(NSURL *url))completionHandler {
    NSURL *url = self;
    
    if (@available(iOS 11, *)) {
        [[NSFileManager defaultManager] getFileProviderServicesForItemAtURL:url completionHandler:^(NSDictionary<NSFileProviderServiceName,NSFileProviderService *> * _Nullable services, NSError * _Nullable error) {
            BOOL didFindService = NO;
            
            for (NSFileProviderServiceName serviceName in services.allKeys) {
                if ([serviceName hasSuffix:@"x-document-source"]) {
                    // found a service ending in "x-document-source"!
                    didFindService = YES;
                    
                    NSFileProviderService *service = services[serviceName];
                    // try to connect to service
                    [service getFileProviderConnectionWithCompletionHandler:^(NSXPCConnection * _Nullable connection, NSError * _Nullable error) {
                        if (error != nil) {
                            NSLog(@"requestXDocumentSourceServiceForURL: failed to get file provider connection for x-documents-source service: %@", error);
                            dispatch_async(dispatch_get_main_queue(), ^{
                                completionHandler(url);
                            });
                        } else if (connection) {
                            connection.remoteObjectInterface = [NSXPCInterface interfaceWithProtocol:@protocol(XDocumentSourceProtocol)];
                            [connection resume];
                            
                            [[connection remoteObjectProxyWithErrorHandler:^(NSError * _Nonnull error) {
                                NSLog(@"requestXDocumentSourceServiceForURL: error calling remote object: %@", error);
                                dispatch_async(dispatch_get_main_queue(), ^{
                                    completionHandler(url);
                                });
                                [connection invalidate];
                            }] writeExtendedAttributeWithCompletionHandler:^(BOOL didWrite) {
                                NSLog(@"writeExtendedAttributeWithCompletionHandler didWrite:%d", didWrite);
                                dispatch_async(dispatch_get_main_queue(), ^{
                                    completionHandler(url);
                                });
                                [connection invalidate];
                            }];
                        }
                    }];
                    break;
                }
            }
            
            if (!didFindService) {
                // service not found -> call completion handler
                dispatch_async(dispatch_get_main_queue(), ^{
                    completionHandler(url);
                });
            }
        }];
    } else {
        dispatch_async(dispatch_get_main_queue(), ^{
            completionHandler(url);
        });
    }
}

@end