A block sequencer for objective-c based heavily on berzniz's brilliant Sequencer.

It has been expanded upon to allow for the separation of the running of activities and any UI that would report its progress.

Simple Usage

ILActivitySequence *sequence=[ILActivitySequence activitySequence];
[sequence addActivityLabeled:@"Step 1"
                       block:^(ILActivity *activity, id previousResult, ILActivityProgressBlock progressBlock, ILActivityCompleteBlock completeBlock) {
                           NSLog(@"Running activity %@",activity.label);

                           // report some progress
                           progressBlock(activity, 1.0f);

                           // We are done so call the completeBlock, passing this activity's label to the next step
                           completeBlock(YES, activity.label, nil);
                       }];

[sequence addActivityLabeled:@"Step 2"
                       block:^(ILActivity *activity, id previousResult, ILActivityProgressBlock progressBlock, ILActivityCompleteBlock completeBlock) {
                           NSLog(@"Previous activity %@",previousResult);

                           NSLog(@"Running activity %@",activity.label);

                           // report some progress
                           progressBlock(activity, 1.0f);

                           // We are done so call the completeBlock, passing this activity's label to the next step
                           completeBlock(YES, activity.label, nil);
                       }];

[sequence run];

The output looks like:

Running activity Step 1
Previous activity Step 1
Running activity Step 2

In this very basic example, we set up a sequence that runs two steps on a background thread. If we wanted to run it on the current thread and wait for it to finish running, we'd change the last line to:

[sequence runSynchronously];

Once a sequence has run, it will release itself, so you normally wouldn't have to worry about doing that.

However, unlike berzniz's Sequencer, ActivitySequencer doesn't release the steps as the are run. This allows you to create sequences that you can run and run again. In this case, you will need to retain and release the sequence yourself.

Advanced Usage

To help insure separation of concerns and to keep your UI out of your model code, ActivitySequencer allows you to pass in blocks that you can use to report progress through your UI, or just to keep tabs on what is going on.

ILActivitySequence *sequence=[ILActivitySequence activitySequence];
[sequence addActivityLabeled:@"Step 1"
                       block:^(ILActivity *activity, id previousResult, ILActivityProgressBlock progressBlock, ILActivityCompleteBlock completeBlock) {
                           NSLog(@"Running activity %@",activity.label);

                           // report some progress
                           progressBlock(activity, 1.0f);

                           // We are done so call the completeBlock, passing this activity's label to the next step
                           completeBlock(YES, activity.label, nil);
                       }];

[sequence addActivityLabeled:@"Step 2"
                       block:^(ILActivity *activity, id previousResult, ILActivityProgressBlock progressBlock, ILActivityCompleteBlock completeBlock) {
                           NSLog(@"Previous activity %@",previousResult);

                           NSLog(@"Running activity %@",activity.label);

                           // report some progress
                           progressBlock(activity, 1.0f);

                           // We are done so call the completeBlock, passing this activity's label to the next step
                           completeBlock(YES, activity.label, nil);
                       }];

[sequence run:^(ILActivity *activity, NSInteger totalSteps) {
        NSLog(@"Step %d - '%@' started.",activity.step,activity.label);
    }
         progress:^(ILActivity *activity, float progress) {
             NSLog(@"Step %d - '%@' progress: %f.",activity.step,activity.label,progress);
         }
              end:^(ILActivity *activity, NSInteger totalSteps) {
                  NSLog(@"Step %d - '%@' ended.",activity.step,activity.label);
              }
            error:^(ILActivity *activity, NSError *error) {
                NSLog(@"Step %d - '%@' error: %@",activity.step,activity.label,[error localizedDescription]);
            }];

You'll see that the run message has 4 block parameters. The first block is called right before the step is run. The second block is the progress block that each activity will call. The third block is called after the step is run. The fourth block is called if the step doesn't run successfully.

The output looks like:

Step 1 - 'Step 1' started.
Running activity Step 1
Step 1 - 'Step 1' progress: 1.000000.
Step 1 - 'Step 1' ended.
Step 2 - 'Step 2' started.
Previous activity Step 1
Running activity Step 2
Step 2 - 'Step 2' progress: 1.000000.
Step 2 - 'Step 2' ended.

Xcode Template

You can install the Xcode template by copying the Activity Sequence folder in the Xcode Templates folder to:

~/Library/Developer/Xcode/Templates/File Templates

CocoaPods

ActivitySequencer can be included via the CocoaPods package manager.

Install CocoaPods if not already available:

$ [sudo] gem install cocoapods
$ pod setup

Edit your Podfile and add ActivitySequencer:

$ edit Podfile
pod 'ActivitySequencer'

Install into your Xcode project:

$ pod install

License

Copyright (c) 2013, Jon Gilkison All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Thanks

Thanks to Tal Bereznitskey for his original idea.