How do you make a selector in Swift?
In Swift, Objective-C selectors are represented by the Selector structure, and you create them using the #selector expression. In Swift, create a selector for an Objective-C method by placing the method name inside the #selector expression: #selector(MyViewController.tappedButton(_:)) .
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What is an NSException?
NSException(IntPtr) A constructor used when creating managed representations of unmanaged objects; Called by the runtime. NSException(NSCoder) A constructor that initializes the object from the data stored in the unarchiver object.
Why is an unrecognized selector sent to the instance in Swift?
The Swift compiler can’t check if the function actually exists before running your app, so if you’ve written the selector incorrectly, you’ll get that Unrecognized selector sent to the instance. If Swift had been able to check if the selector exists when building the app, it would have thrown the Unresolved Identifier Usage error.
Can a selector be checked at runtime in Swift?
The string with the selector cannot be checked at runtime! The Swift compiler can’t check if the function actually exists before running your app, so if you’ve written the selector incorrectly, you’ll get that Unrecognized selector sent to the instance.
What does unrecognized selector sent to instance mean in Xcode?
One of the most common errors in Xcode is “Unrecognized selector sent to instance”. Today I will try to explain why we are getting this error and most importantly how to fix it. But before we start digging into the code, we need to better understand the error message in the console area.
Why is the selector not autocomplete in Swift 4?
This is because Swift 4 does not automatically make Swift functions available to Objective-C. However, the peculiar way of writing functions with underscores and colons is maintained. Fortunately, you can use code completion to get suggestions, like this: just place your cursor between the #selector() parentheses and press the Esc key.