Ad view used to measure viewability. This property can be modified before or after starting
display ad measurement. Must be accessed on the main thread.
Starts OMID viewability measurement for display ads. Returns whether OMID viewability was
started and sets |error| if unable to start. Once started, all subsequent calls return YES and
have no effect. Must be called on the main thread.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2021-02-23 UTC."],[],[]]