- I am very happy Swift does not have exceptions, I much rather hope to see a later addition of Computational Expressions or so.
- I do not want to encourage you to use exceptions.
- By default exceptions leak memory when combined with ARC (you can use
clang -fobjc-arc-exceptions). - Unfortunately, there are times when you can't get around catching an exception (
NSTask,NSFileHandle, KVO, ...) in Cocoa and currently Swift doesn't allow you to do so. - This is a quick prototype not ready for production probably.
- This repo contains a full Xcode project including all the code (Swift and ObjC).
The following interface
@interface JFWSwiftExceptionBridge : NSObject
+ (void)swiftBridgeTry:(void(^)(void))tryBlock
except:(void(^)(NSException *))exceptBlock
finally:(void(^)(void))finallyBlock;
+ (void)swiftBridgeTry:(void(^)(void))tryBlock
except:(void(^)(NSException *))exceptBlock;
+ (JFWResultOrException *)swiftBridgeResultTry:(id(^)(void))tryBlock;
@end
does allow you to use them from Swift (full swift example). Example:
A full try/catch/finally:
JFWSwiftExceptionBridge.swiftBridgeTry({
exceptionThrowingFunction()
},
except: {
print("CAUGHT EXCEPTION: \($0)\n")
},
finally: {
() -> Void in
print("FINALLY\n")
})
Try/catch only:
JFWSwiftExceptionBridge.swiftBridgeTry(exceptionThrowingFunction,
except: {
print("CAUGHT EXCEPTION: \($0)\n")
})
Or rather an Either-like type which wraps either the result (type id) as returned from the function or the exception if the function threw an exception:
let roe = JFWSwiftExceptionBridge.swiftBridgeResultTry { () -> AnyObject! in
return exceptionTrowingFunctionWithResult()
}
print("RESULT OR EXCEPTION: \(roe)\n")
The output then looks either like
RESULT OR EXCEPTION: Result(works)
if it worked and the string "works" was returned, or like that
RESULT OR EXCEPTION: Exception(<DESCRIPTION OF EXCEPTION>)
if an exception appeared.