iOS Class Chain Strategy
This query type is WebDriverAgent's layer over native XCTest lookup function calls defined in XCUIElementQuery class with some additional features, like intermediate chain items indexing and tail-based indexing. Search by direct children and descendant elements is supported.
The final option is a sort of hybrid between XPath and predicate strings: the -ios class chain locator strategy. This was developed by the Appium team to meet the need of hierarchical queries in a more performant way. The types of queries possible via the class chain strategy are not as powerful as those enabled by XPath, but this restriction means a better performance guarantee (this is because it is possible to map class chain queries into a series of direct XCUITest calls, rather than having to recursively build an entire UI tree). Class chain queries look very much like XPath queries, however, the only allowed filters are basic child/descendant indexing or predicate string matching. It’s worth checking out the class chain docs to find a number of examples. Let’s take a look at just a couple:
iOS Predicate String Strategy
Predicate queries are natively supported by XCTest and enable the quick location of elements based on their attribute values.
Follow the rules described in Predicate Format String Syntax article.
Predicate Format Strings are a typical Apple dev thing, and they also work in iOS. Predicate format strings enable basic comparisons and matching. In our case, they allow the basic matching of elements according to simple criteria. What’s really useful about predicate strings is that you can combine simple criteria to form more complex matches. In the XCUITest driver, predicate strings can be used to match various element attributes, including name, value, label, type, visible, etc…
Watch the full video to understand how you can make use of the iOS Class chain and iOS predicate string to get rid of XPath completely.
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