Normally you’ll want to use [error localizedDescription] to get the text to show to the user. Read the NSError documentation for more options. For simple logging when developing, you can do NSLog(@”Error: %@”, error). (That will give you ‘localizedDescription’ and everything else on your log in Xcode.)
You need to take the address of error because the function needs to modify it. error is passed by pointer, so you need the “take address” operator & for it. C and Objective-C pass parameters by value. If you pass error without an ampersand and the method that you call modifies it, your function that … Read more
NSError is a Cocoa class An NSError object encapsulates information about an error condition in an extendable, object-oriented manner. It consists of a predefined error domain, a domain-specific error code, and a user info dictionary containing application-specific information. Error is a Swift protocol which classes, structs and enums can and NSError does conform to. A … Read more
There is no HTTP status code 0. What you see is a 0 returned by the API/library that you are using. You will have to check the documentation for that.
-[NSError localizedDescription]. (Also, every ObjC object inherited from NSObject implements -description which returns an NSString.)
These types and methods have changed a lot since Swift 1. The NS prefix is dropped The methods now throw exceptions instead of taking an error pointer Use of NSDictionary is discouraged. Instead use a Swift dictionary This results in the following code: do { let object = try JSONSerialization.jsonObject( with: responseData, options: .allowFragments) if … Read more
Looks like you want (see dictionary keys): Swift 2 let userInfo: [NSObject : AnyObject] = [ NSLocalizedDescriptionKey : NSLocalizedString(“Unauthorized”, value: “Please activate your account”, comment: “”), NSLocalizedFailureReasonErrorKey : NSLocalizedString(“Unauthorized”, value: “Account not activated”, comment: “”) ] Swift 3 let userInfo: [AnyHashable : Any] = [ NSLocalizedDescriptionKey : NSLocalizedString(“Unauthorized”, value: “Please activate your account”, comment: “”) … Read more
It is unsafe to throw exceptions in circumstances where resources are not automatically managed. This is the case of the Cocoa framework (and neighbor frameworks), as they use manual reference counting. If you throw an exception, any release call you skip over by unwinding the stack will result in a leak. This should limit you … Read more
I personally use a reverse-DNS style domain. For example: NSError * myInternalError = [NSError errorWithDomain:@”com.davedelong.myproject” code:42 userInfo:someUserInfo]; The third part of the domain (@”myproject”) is just used to differentiate the errors from this project (“My Project”) from errors in another project (“My Other Project” => com.davedelong.myotherproject). It’s a simple way to ensure that I’m not … Read more
Well, what I usually do is have my methods that could error-out at runtime take a reference to a NSError pointer. If something does indeed go wrong in that method, I can populate the NSError reference with error data and return nil from the method. Example: – (id) endWorldHunger:(id)largeAmountsOfMonies error:(NSError**)error { // begin feeding the … Read more