These materials are for informational purposes only and do not constitute legal advice. You should contact an attorney to obtain advice with respect to the development of a research app and any applicable laws.

Creating Surveys

A survey is composed of a sequence of questions that you use to collect data from your users. To start a survey, you create a survey task, which is a collection of step objects (ORKStep). Each step object handles a specific question in the survey, such as “What medications are you taking?” or “How many hours did you sleep last night?”

You can collect results for the individual steps or for the entire task. There are two types of survey tasks that you can create: an ordered task (ORKOrderedTask) and a navigable ordered task (ORKNavigableOrderedTask).

In an ordered task, the order that the steps appear are always the same.

An example of a survey that uses ordered tasks.

In a navigable ordered task, the order of the tasks can change, or branch out, depending on how the user answered a question in a previous task.

An example of a survey that uses navigable ordered tasks.

The steps for creating a task to present a survey are:

  1. Create one or more steps
  2. Create a task
  3. Collect results

1. Create Steps

The survey module provides a single-question step (ORKQuestionStep) and a form step that can contain more than one item (ORKFormStep). You can also use an instruction step (ORKInstructionStep) to introduce the survey or provide specific instructions.

Every step has its own step view controller that defines the UI presentation for that type of step. When a task view controller needs to present a step, it instantiates and presents the right step view controller for the step. If needed, you can customize the details of each step view controller, such as button titles and appearance, by implementing task view controller delegate methods (see ORKTaskViewControllerDelegate).

Instruction Step

An instruction step explains the purpose of a task and provides instructions for the user. An ORKInstructionStep object includes an identifier, title, text, detail text, and an image. Because an instruction step does not collect any data, it yields an empty ORKStepResult that nonetheless records how long the instruction was on screen.

    ORKInstructionStep *step =
      [[ORKInstructionStep alloc] initWithIdentifier:@"identifier"];
    step.title = @"Selection Survey";
    step.text = @"This survey can help us understand your eligibility for the fitness study";

Creating a step as shown in the code above, including it in a task, and presenting with a task view controller, yields something like this:

Instruction step
Example of an instruction step.

Question Step

A question step (ORKQuestionStep) presents a single question, composed of a short title and longer, more descriptive text. Configure the type of data the user can enter by setting the answer format. You can also provide an option for the user to skip the question with the step’s optional property.

For numeric and text answer formats, the question step’s placeholder property specifies a short hint that describes the expected value of an input field.

A question step yields a step result that, like the instruction step’s result, indicates how long the user had the question on screen. It also has a child, an ORKQuestionResult subclass that reports the user’s answer.

The following code configures a simple numeric question step:

    ORKNumericAnswerFormat *format =
      [ORKNumericAnswerFormat integerAnswerFormatWithUnit:@"years"];
    format.minimum = @(18);
    format.maximum = @(90);
    ORKQuestionStep *step =
      [ORKQuestionStep questionStepWithIdentifier:kIdentifierAge
                                            title:@"How old are you?"

Adding this question step to a task and presenting the task produces a screen that looks like this:

Question step
Example of a question step.

Form Step

When the user needs to answer several related questions together, it may be preferable to use a form step (ORKFormStep) in order to present them all on one page. Form steps support all the same answer formats as question steps, but can contain multiple items (ORKFormItem), each with its own answer format.

Forms can be organized into sections by incorporating extra “dummy” form items that contain only a title. See the ORKFormItem reference documentation for more details.

The result of a form step is similar to the result of a question step, except that it contains one question result for each form item. The results are matched to their corresponding form items using their identifiers (the identifier property).

For example, the following code shows how to create a form that requests some basic details, using default values extracted from HealthKit on iOS to accelerate data entry:

    ORKFormStep *step =
    [[ORKFormStep alloc] initWithIdentifier:kFormIdentifier
                                        text:@"Form groups multi-entry in one page"];
    NSMutableArray *items = [NSMutableArray new];
    ORKAnswerFormat *genderFormat =
         [HKCharacteristicType characteristicTypeForIdentifier:HKCharacteristicTypeIdentifierBiologicalSex]];
    [items addObject:
      [[ORKFormItem alloc] initWithIdentifier:kGenderItemIdentifier

    // Include a section separator
    [items addObject:
      [[ORKFormItem alloc] initWithSectionTitle:@"Basic Information"]];

    ORKAnswerFormat *bloodTypeFormat =
         [HKCharacteristicType characteristicTypeForIdentifier:HKCharacteristicTypeIdentifierBloodType]];
    [items addObject:
      [[ORKFormItem alloc] initWithIdentifier:kBloodTypeItemIdentifier
                                         text:@"Blood Type"

    ORKAnswerFormat *dateOfBirthFormat =
         [HKCharacteristicType characteristicTypeForIdentifier:HKCharacteristicTypeIdentifierDateOfBirth]];
    ORKFormItem *dateOfBirthItem =
      [[ORKFormItem alloc] initWithIdentifier:kDateOfBirthItemIdentifier
    dateOfBirthItem.placeholder = @"DOB";
    dateOfBirthItem.optional = YES;
    [items addObject:dateOfBirthItem];

    // ... And so on, adding additional items
    step.formItems = items;

The code above gives you something like this:

Form step
Example of a form step.

The ORKFormItem has an boolean property named optional which affects navigation to subsequent steps. It is set to NO by default, which requires the user to set that item before they can continue. If the property is set to YES, then the user can continue to the next step without setting the item. In the above code snipping, the optional property is for the dateOfBirth object is set to YES. This lets the user continue to the next step without putting in their date of birth.

Answer Format

In the ResearchKitâ„¢ framework, an answer format defines how the user should be asked to answer a question or an item in a form. For example, consider a survey question such as “On a scale of 1 to 10, how much pain do you feel?” The answer format for this question would naturally be a discrete scale on that range, so you can use scale answer format (ORKScaleAnswerFormat), and set its minimum and maximum properties to reflect the desired range.

The screenshots below show the standard answer formats that the ResearchKit framework provides.

Scale answer format

Boolean answer format

Value picker answer format

Image choice answer format

Text choice answer format (single text choice answer)

Text choice answer format (multiple text choice answer)

Numeric answer format

TimeOfTheDay answer format

Date answer format

Text answer format (unlimited text entry)

Text answer format (limited text entry)

Validated text answer format

Scale answer format (vertical)

Email answer format

Location answer format

In addition to the preceding answer formats, the ResearchKit framework provides special answer formats for asking questions about quantities or characteristics that the user might already have stored in the Health app. When a HealthKit answer format is used, the task view controller automatically presents a Health data access request to the user (if they have not already granted access to your app). The presentation details are populated automatically, and, if the user has granted access, the field defaults to the current value retrieved from their Health database.

2. Create a Survey Task

Once you create one or more steps, create an ORKOrderedTask object to hold them. The code below shows a Boolean step being added to a task.

    // Create a Boolean step to include in the task.
    ORKStep *booleanStep = 
      [[ORKQuestionStep alloc] initWithIdentifier:kNutritionIdentifier];
    booleanStep.title = @"Do you take nutritional supplements?";
    booleanStep.answerFormat = [ORKBooleanAnswerFormat new];
    booleanStep.optional = NO;
    // Create a task wrapping the boolean step.
    ORKOrderedTask *task =
      [[ORKOrderedTask alloc] initWithIdentifier:kTaskIdentifier

You must assign a string identifier to each step. The step identifier should be unique within the task, because it is the key that connects a step in the task hierarchy with the step result in the result hierarchy.

To present the task, attach it to a task view controller and present it. The code below shows how to create a task view controller and present it modally.

    // Create a task view controller using the task and set a delegate.
    ORKTaskViewController *taskViewController =
      [[ORKTaskViewController alloc] initWithTask:task taskRunUUID:nil];
    taskViewController.delegate = self;

    // Present the task view controller.
    [self presentViewController:taskViewController animated:YES completion:nil];

Note: ORKOrderedTask assumes that you will always present all the questions, and will never decide what question to show based on previous answers. To introduce conditional logic, you must either subclass ORKOrderedTask or implement the ORKTask protocol yourself.

3. Collect Results

The result property of the task view controller gives you the results of the task. Each step view controller that the user views produces a step result (ORKStepResult). The task view controller collates these results as the user navigates through the task, in order to produce an ORKTaskResult.

Both the task result and step result are collection results, in that they can contain other result objects. For example, a task result contains an array of step results.

The results contained in a step result vary depending on the type of step. For example, a question step produces a question result (ORKQuestionResult); a form step produces one question result for every form item; and an active task with recorders generally produces one result for each recorder.

The hierarchy of results corresponds closely to the input model hierarchy of task and steps, as you can see here:

Completion step
Example of a result hierarchy

Among other properties, every result has an identifier. This identifier is what connects the result to the model object (task, step, form item, or recorder) that produced it. Every result also includes start and end times, using the startDate and endDate properties respectively. These properties can be used to infer how long the user spent on the step.

Step Results That Determine the Next Step

Sometimes it’s important to know the result of a step before presenting the next step. For example, suppose a step asks “Do you have a fever?” If the user answers Yes, the next question the next question might be “What is your temperature now?”; otherwise it might be, “Do you have any additional health concerns?”

To add custom conditional behavior in your task, use either ordered task (ORKOrderedTask) or navigable ordered task (ORKNavigableOrderedTask), and override particular ORKTask methods like stepAfterStep:withResult, and stepBeforeStep:withResult: and call super for all other methods.

Ordered Tasks

A sequential (static) task, such as a survey or an active task, can be represented as an ordered task.

The following example demonstrates how to subclass ORKOrderedTask to provide a different set of steps depending on the user’s answer to a Boolean question. Although the code shows the step-after-step method, a corresponding implementation of “step-before-step” is usually necessary.

    - (ORKStep *)stepAfterStep:(ORKStep *)step
                    withResult:(idORKTaskResultSource)result {
        NSString *identifier = step.identifier;  
        if ([identifier isEqualToString:self.qualificationStep.identifier])
            ORKStepResult *stepResult = [result stepResultForStepIdentifier:identifier];
            ORKQuestionResult *result = (ORKQuestionResult *)stepResult.firstResult;
            if ([result isKindOfClass:[ORKBooleanQuestionResult class]])
                ORKBooleanQuestionResult *booleanResult = result;
                NSNumber *booleanAnswer = booleanResult.booleanAnswer;
                if (booleanAnswer)
                    return booleanAnswer.boolValue ? self.regularQuestionStep : self.terminationStep;
        return [super stepAfterStep:step withResult:result];

Navigable Ordered Task

The navigable ordered task (ORKNavigableOrderedTask) inherits its behavior from the ordered task (ORKOrderedTask) class. In addition to inheriting the behavior of ordered task it provides functionality to present different set of steps depending on the user’s answer to a question.

You can add a condition while the user navigates through the steps in a task by adding a conditional step navigation. For example, add a navigation rule to obtain a new destination step when the user goes forward from one step to another. You cannot add more than one navigation rule to the same step. If you do, then the most recent rule is executed.

For example, to display a survey question only when the user answered Yes to a previous question you can use ORKPredicateStepNavigationRule; or if you want to define an arbitrary jump between two steps, you can use ORKDirectStepNavigationRule.

The following example demonstrates how you can add a navigation rule to go to different step in the task depending on the user’s selection to the symptom type. For example, from the “symptom” step, go to “other_symptom” step when the user didn’t chose headache. Otherwise, default to going to next step (the regular ordered task (ORKOrderedTask) applies).

    ORKNavigableOrderedTask *task = [[ORKNavigableOrderedTask alloc] initWithIdentifier:StepNavigationTaskIdentifier steps:steps];

    // Build a navigation rule
    ORKPredicateStepNavigationRule *predicateRule = nil;

    NSPredicate *predicateHeadache = [ORKResultPredicate predicateForChoiceQuestionResultWithResultIdentifier:@"symptom" expectedString:@"headache"];

    // The user didn't choose headache at the symptom step
    NSPredicate *predicateNotHeadache = [NSCompoundPredicate notPredicateWithSubpredicate:predicateHeadache];

    predicateRule = [[ORKPredicateStepNavigationRule alloc] initWithResultPredicates:@[ predicateNotHeadache ]
                                                          destinationStepIdentifiers:@[ @"other_symptom" ] ];

    [task setNavigationRule:predicateRule forTriggerStepIdentifier:@"symptom"];

Saving Results on Task Completion

After the task is completed, you can save or upload the results. This approach will likely include serializing the result hierarchy in some form, either using the built-in NSSecureCoding support, or another format appropriate for your application.

If your task can produce file output, the files are generally referenced by an ORKFileResult object and they are placed in the output directory that you set on the task view controller. After you complete a task, one implementation might be to serialize the result hierarchy into the output directory, zip up the entire output directory, and share it.

In the following example, the result is archived with NSKeyedArchiver on successful completion. If you choose to support saving and restoring tasks, the user may save the task, so this example also demonstrates how to obtain the restoration data that would later be needed to restore the task.

    - (void)taskViewController:(ORKTaskViewController *)taskViewController
                         error:(NSError *)error
        switch (reason) {
        case ORKTaskViewControllerFinishReasonCompleted:
            // Archive the result object first
            NSData *data = [NSKeyedArchiver archivedDataWithRootObject:taskViewController.result];

            // Save the data to disk with file protection
            // or upload to a remote server securely.

            // If any file results are expected, also zip up the outputDirectory.
        case ORKTaskViewControllerFinishReasonFailed:
        case ORKTaskViewControllerFinishReasonDiscarded:
            // Generally, discard the result.
            // Consider clearing the contents of the output directory.
        case ORKTaskViewControllerFinishReasonSaved:
            NSData *data = [taskViewController restorationData];
            // Store the restoration data persistently for later use.
            // Normally, keep the output directory for when you will restore.