danchoys / dkcompoundoperation

DKCompoundOperation

This easy-to-use and lightweight component allows to organize operations in sequences, providing a single interface for progress and completion tracking. It also makes possible the cancellation of the whole compound operation through the NSProgress instance.

Usage

The following code shows how to make a three-step operation of exporting video from ALAssetsLibrary, uploading the result to the remote server and performing some necessary cleanup. It assumes that there are two classed: ExportVidoOperation and UploadVideoOperation, inheriting from DKOperation.

import <DKCompoundOperation/DKCompoundOperation.h>

static NSInteger const kExportOperationProgressFraction = 30;
static NSInteger const kUploadOperationProgressFraction = 65;
static NSInteger const kCleanupOperationProgressFraction = 5;

<...>

@property (nonatomic, strong) NSOperationQueue *queue;
@property (nonatomic, weak) NSProgress *progress;

<...>

DKCompoundOperation *operation = [[DKCompoundOperation alloc] init];
[operation addOperationCreatedUsingBlock:^DKOperation *{
    return [ExportVideoOperation operationWithVideoAssetURL:assetURL];
} progressFraction:kExportOperationProgressFraction];
[operation addOperationCreatedUsingBlock:^DKOperation *{
    return [UploadVideoOperation operation];
} progressFraction:kUploadOperationProgressFraction];
[operation addOperationWithOperationBlock:^(DKOperation *operation) {
    operation.progress.totalUnitCount = 150;
    // Perform some cleanup operations 
    // updating operation.progress
    operation.completeOperation(YES, nil);
} progressFraction:kCleanupOperationProgressFraction];
operation.completionBlock = ^(BOOL success, NSError *error) {
    if (error) {
        NSLog(@"Error occured: %@", error);
        return;
    }
    self.completedLabel.hidden = NO;
};
self.progress = operation.progress;
[self.queue addCompoundOperation:operation];

You may track changes to the progress object using KVO. For more information, visit the NSProgress Class Reference and Key-Value Observing Guide.

Installation

DKCompoundOperation is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "DKCompoundOperation"

Author

Daniil Konoplev, [email protected]

License

DKCompoundOperation is available under the MIT license. See the LICENSE file for more info.