nskeyedunarchiver

As I understand, the use of @try/@catch blocks is discouraged, because exceptions should only be thrown at unrecoverable, catastrophic errors (refer to this discussion with a nice answer by @bbum : Exception Handeling in iOS ). So I looked through my code and found a @try/@catch block that I don't know how to get rid of: NSData *fileData = [NSData dataWithContentsOfFile: ....]; NSDictionary *dictionary; @try { dictionary = [NSKeyedUnarchiver unarchiveObjectWithData: fileData]; } @catch (NSException *exception) { //.... } @finally { //... } The problem is that (as stated in the documentation )

I have a pretty trivial Swift app that has a model class named DemoNote . An array of DemoNote instances is read/written via keyed archiving. This worked fine while DemoNote was included in the app. But then I moved DemoNote.swift to a new custom framework called DemoSharedCode . Aside from making sure Xcode was using the framework in the app target, I made sure to Mark DemoNote and its vars and methods as public so they'd be visible outside of the framework Add import DemoSharedCode to any classes that want to use DemoNote So now the compiler is happy. But at run time the unarchiving fails

NSKeyedUnarchiver.decodeObject will cause a crash / SIGABRT if the original class is unknown. The only solution I have seen to catching this issue dates from Swift's early history and required using Objective C (also pre-dated Swift 2's implementation of guard , throws , try & catch ). I could figure out the Objective C route - but I would prefer to understand a Swift-only solution if possible. For example - the data has been encoded with NSPropertyListFormat.XMLFormat_v1_0 . The following code will fail at unarchiver.decodeObject() if the class of the encoded data is unknown. //... let dat =

Since upgrading to Swift 4.2 I've found that many of the NSKeyedUnarchiver and NSKeyedArchiver methods have been deprecated and we must now use the type method static func unarchivedObject<DecodedObjectType>(ofClass: DecodedObjectType.Type, from: Data) -> DecodedObjectType? to unarchive data. I have managed to successfully archive an Array of my bespoke class WidgetData, which is an NSObject subclass: private static func archiveWidgetDataArray(widgetDataArray : [WidgetData]) -> NSData { guard let data = try? NSKeyedArchiver.archivedData(withRootObject: widgetDataArray as Array,