FCYAsserts

Inspired by Friday Q&A 2013-05-03: Proper Use of Asserts I made these macros to handle my assertions.

Be Aware: I don't disable the asserts in release code. I agree with Mike Ash that if something is wrong it should break ASAP.

Assert or Return

Inspired by Krzysztof Zabłocki blog post, macros of the family FCYAssertOrReturn does not crash the app in release builds only in debug. Why this? An app shouldn't crash because of an external change.

Important Note: FCYAssertOrReturn uses NS_BLOCK_ASSERTIONS just like NSAssert.

When Should I Use One Or The Other?

FCYAssert, if you have control over the caller code;
FCYAssertOrReturn, if you are asserting external code, for example, if a JSON root element is a NSDictionary.

Installation

Using CocoaPods

In your Podfile add this line:

pod 'FCYAsserts'

Old School

Just add the files in FCYAsserts and import FCYAsserts.h in your prefix header (*.pch) or directly in each .m you want.

Usage

FCYAssert

The usage is exactly like NSAssert the difference is that the log is more complete.

// AppDelegate.m

#import "FCYAsserts.h"

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    [self startLengthyOperation];
    // ...
}

- (void)startLengthyOperation {
    FCYAssertIsNotInMainThread;
    // ...
}

Would abort with the following log using, by default, NSLog:

-[TPAppDelegate startLengthyOperation]: Assertion '(![NSThread isMainThread])' failed on line /Users/you/dev/Project/AppDelegate.m:56. This should not be running on the main thread.

FCYAssertOrReturn

NSError *error;
id json = [NSJSONSerialization JSONObjectWithData:dataFromServer options:0 error:&error];
if (error) {
    completionBlock(nil, error);
} else {
    FCYAssertOrReturnBlock([json isKindOfClass:[NSDictionary class]], @"Invalid Server Data", ^(NSError *assertError){
        completionBlock(nil, assertError);
    });

    completionBlock(json, nil);
}

If json is not a NSDictionary in debug code it would abort and log and in release it would just log:

-[MyClass callServiceWithCompletionBlock:]: Assertion '[json isKindOfClass:[NSDictionary class]]' failed on line /Users/you/dev/Project/MyClass.m:42. Invalid Server Data

Log messages with CocoaLumberjack

If you use CocoaLumberjack you can make FCYAsserts use it by defining FCYAssertLog:

#import "FCYAsserts.h"
#define FCYAssertLog DDLogError

With CocoaLumberjack you can save your logs into a file, and much more. Which is very useful to support request, you could attach the logs when the user send a support request from within your app.

And it is faster than NSLog.

Enjoy!

License

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

fcy/FCYAsserts