How to Resolve “This Class is Not Key Value Coding-Compliant” Error in Xcode
1 min read
Summary
The ‘NSUnknownKeyException’ error in Xcode is a common issue for iOS and Mac app developers, which occurs when a runtime attempt is made to set a value for a non-existent property.
The error can be difficult to debug, and its cause can be human error, such as incorrect outlet connections or typos in property names.
In this article, we explore what Key-Value Coding (KVC) is, how it can lead to this error, and how developers can debug and prevent the issue.
The article also highlights useful tips, including the need for developers to pay attention to mixed-language projects, where Swift and Objective-C interoperability can cause problems if properties are not correctly marked with an
@objc
annotation.
Overall, by understanding how KVC works and adopting strict debugging and housekeeping practices, programmers can save time that would otherwise be spent trawling through code trying to identify the cause of the mistake.