Adding Try-Catch to Swift

I’m addicted to Swift. As a legacy Objective-C developer, I’ve had a blast over the last few months using Swift. However, I’ve found the lack of try/catch a little infuriating.

I’ll walk you through implementing your own try-catch for Swift. If you need it fast, download the code here.

Strategy

We’re going to build a wrapper around the traditional Objective-c try-catch and pass in Swift closures to execute as part of the code.

Steps:

• Create a new Objective-c class. Pick NSObject as the subclass.

• Allow Xcode to add a bridging header if you don’t already have one. The bridging header allows Swift code to access Objective-c classes imported through there.

• Make your TryCatch class visible to the Swift project by importing the Objective-c header.

• Declare your new try-catch function. We’re using a + to make it a class function for easy use.

+ (void)try:void(^)())try catch:void(^)(NSException*exception))catch finally:void(^)())finally;

• Implement the function using the default Objective-c try-catch.

• Call the closures (blocks) inside each matching part of the try-catch. Only call if the closure (block) isn’t nil.

+(void)try:void (^)())try catch:void (^)(NSException *))catch finally:void (^)())finally{
    @try {
       try ? try() : nil;
    }
    @catch (NSException *exception) {
       catch ? catch(exception) : nil;
    }
    @finally {
       finally ? finally() : nil;
    }
}

Usage

Use anywhere you need a try catch in your Swift project.

 TryCatch.try({ () -> Void in
    //try stuff
 }, catch: { (exception) -> Void in
    //catch exceptions
 }) { () -> Void in
    //close resources
 }

Download the full code

https://github.com/williamFalcon/SwiftTryCatch

Harlem App Collective is a design focused, mobile development shop based in Harlem, NY. Email: hi@hacstudios.com