#nserror

Answer: How can I use NSError in my iPhone App? #dev #it #answer

How can I use NSError in my iPhone App?

I am working on catching errors in my app, and I am looking into using NSError. I am slightly confused about how to use it, and how to populate it.

Could someone provide an example on how I populate then use NSError?

Answer [by Senseful]: How can I use NSError in my iPhone App?

Another design pattern that I have seen involves using blocks, which is…

How to: How can I use NSError in my iPhone App?

How can I use NSError in my iPhone App?

I am working on catching errors in my app, and I am looking into using NSError. I am slightly confused about how to use it, and how to populate it.

Could someone provide an example on how I populate then use NSError?

Answer: How can I use NSError in my iPhone App?

Please refer following tutorial

i hope it will helpful for you but prior you have to read…

Exceptions (represented by NSException objects) are for programming errors, such as an array index that is out of bounds or an invalid method argument. User-level errors (represented byNSError objects) are for runtime errors, such as when a file cannot be found or a string in a certain encoding cannot be read. Conditions giving rise to exceptions are due to programming errors; you should deal with these errors before you ship a product. Runtime errors can always occur, and you should communicate these (via NSError objects) to the user in as much detail as is required.

from here

Sometimes we need to go back to the basics. If possible don't use @try/@catch, instead create a NSError instance and return it by reference, such as:

NSErrorで、以下の様なメッセージが出て怒られてしまった。

Potential null dereference. Accordning to coding standards in 'Creating and Returning NSError Objects' the parameter maybe null

以下の様な実装をしていたのだが、

- (void)testHoge:(NSError *__autoreleasing *)error { ... *error = [NSError errorWithDomain:@"ErrorDomain" code:1 userInfo:nil]; }

errorがNullの可能性があるので、errorにNSErrorを代入する前にチェックが必要だった。