# ExceptionCatcher

> Catch [Objective-C exceptions](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Exceptions/Tasks/HandlingExceptions.html) in Swift

There are many Cocoa APIs that can throw exceptions that cannot be caught in Swift (`NSKeyedUnarchiver`, `NSTask`,  `NSObject#value(forKey:)`, etc). This package wraps an Objective-C exception handler to make it possible to catch such exceptions.

*The ability to catch exceptions should really be built into Swift. If you agree, duplicate [this](https://github.com/feedback-assistant/reports/issues/74) Feedback Assistant report.*

## Install

Add the following to `Package.swift`:

```swift
.package(url: "https://github.com/sindresorhus/ExceptionCatcher", from: "2.2.1")
```

[Or add the package in Xcode.](https://developer.apple.com/documentation/xcode/adding_package_dependencies_to_your_app)

## Usage

```swift
import Foundation
import ExceptionCatcher

final class Foo: NSObject {}

do {
	let value = try ExceptionCatcher.catch {
		return Foo().value(forKey: "nope")
	}

	print("Value:", value)
} catch {
	print("Error:", error.localizedDescription)
	//=> Error: [valueForUndefinedKey:]: this class is not key value coding-compliant for the key nope.

	debugPrint(error)
	/*
	Error Domain=NSUnknownKeyException Code=0 "[valueForUndefinedKey:]: this class is not key value coding-compliant for the key nope." UserInfo={CallStackSymbols=(
	0   CoreFoundation                      0x00007fff361798ab __exceptionPreprocess + 250
	1   libobjc.A.dylib                     0x00007fff6c3ea805 objc_exception_throw + 48
	2   CoreFoundation                      0x00007fff361a230c -[NSException raise] + 9
	3   Foundation                          0x00007fff388f86c4 -[NSObject(NSKeyValueCoding) valueForUndefinedKey:] + 222
	4   Foundation                          0x00007fff3876f8fd -[NSObject(NSKeyValueCoding) valueForKey:] + 317
	5   ExceptionCatcherTests               0x0000000103402ef6 $s21ExceptionCatcherTestsAAC9testCatchyyKFypSgyXEfU1_ + 118
	…
	*/
}
```

## Related

- [Defaults](https://github.com/sindresorhus/Defaults) - Swifty and modern UserDefaults
- [LaunchAtLogin](https://github.com/sindresorhus/LaunchAtLogin) - Add “ Launch at Login” functionality to your macOS app
- [More…](https://github.com/search?q=user%3Asindresorhus+language%3Aswift+archived%3Afalse&type=repositories)