Backtrace

Backtrace's integration with iOS, macOS and tvOS applications allows customers to capture and report handled and unhandled exceptions to their Backtrace instance, instantly offering the ability to prioritise and debug software errors.

Minimal usage

Create the BacktraceClient using init(credentials:) initializer and then send error/exception just by calling method send:

• Swift

import UIKit
import Backtrace

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        let backtraceCredentials = BacktraceCredentials(endpoint: URL(string: "https://backtrace.io")!,
                                                        token: "token")
        BacktraceClient.shared = try? BacktraceClient(credentials: backtraceCredentials)

        do {
            try throwingFunc()
        } catch {
            BacktraceClient.shared?.send { (result) in
                print(result)
            }
        }

        return true
    }
}

• Objective-C

#import "AppDelegate.h"
@import Backtrace;

@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    BacktraceCredentials *credentials = [[BacktraceCredentials alloc]
                                         initWithEndpoint: [NSURL URLWithString: @"https://backtrace.io"]
                                         token: @"token"];
    BacktraceClient.shared = [[BacktraceClient alloc] initWithCredentials: credentials error: nil];

    // sending NSException
    @try {
        NSArray *array = @[];
        NSObject *object = array[1]; // will throw exception
    } @catch (NSException *exception) {
        [[BacktraceClient shared] sendWithException: exception completion:^(BacktraceResult * _Nonnull result) {
            NSLog(@"%@", result);
        }];
    } @finally {

    }

    return YES;
}

@end

Table of contents

1. Features Summary
2. Installation
   • Cocoapods
3. Documentation
   1. Initialize client
   2. Configure client
      • Database settings
      • PLCrashReporter configuration
   3. Events handling
   4. Attributes
   5. Attachments
      1. For crash reports/all reports
      2. Per-report
   6. Sending reports
      1. Error/NSError
      2. NSException
      3. macOS note
4. Beta
   1. Breadcrumbs
   2. Error-free metrics
5. FAQ
   1. Missing dSYM files
      • Finding dSYMs while building project
      • Finding dSYMs while archiving project

Features Summary

• Light-weight client library written in Swift with full Objective-C support that quickly submits exceptions/errors and crashes to your Backtrace dashboard includes:
  • system metadata,
  • machine metadata,
  • signal metadata,
  • exception metadata,
  • thread metadata,
  • process metadata.
• Supports iOS, macOS and tvOS platforms (minimum supported platforms).
• Swift first protocol-oriented framework.

Installation

via CocoaPods

To use CocoaPods just add this to your Podfile:

pod 'Backtrace'

Note: It is required to specify use_frameworks! in your Podfile.

Documentation

Initialize Backtrace client

Initializing Backtrace client requires registration to Backtrace services. You can register to Backtrace services using provided submission url (see: What is a submission url?) and token (see: What is a submission token?). These credentials you can supply using BacktraceCredentials.

• Swift

let backtraceCredentials = BacktraceCredentials(endpoint: URL(string: "https://backtrace.io")!, token: "token")
BacktraceClient.shared = try? BacktraceClient(credentials: backtraceCredentials)

• Objective-C

BacktraceCredentials *backtraceCredentials = [[BacktraceCredentials alloc]
                                             initWithEndpoint: [NSURL URLWithString: @"https://backtrace.io"]
                                             token: @"token"];
BacktraceClient.shared = [[BacktraceClient alloc] initWithCredentials: backtraceCredentials error: error];

Additionally, the BacktraceCredentials object can be initialized using provided URL containing universe and token:

• Swift

let backtraceCredentials = BacktraceCredentials(submissionUrl: URL(string: "https://submit.backtrace.io/{universe}/{token}/plcrash")!)

• Objective-C

BacktraceCredentials *backtraceCredentials = [[BacktraceCredentials alloc] initWithSubmissionUrl: [NSURL URLWithString: @"https://submit.backtrace.io/{universe}/{token}/plcrash"]];

Configure Backtrace client

For more advanced usage of BacktraceClient, you can supply BacktraceClientConfiguration as a parameter. See the following example:

• Swift

let backtraceCredentials = BacktraceCredentials(endpoint: URL(string: "https://backtrace.io")!, token: "token")
let configuration = BacktraceClientConfiguration(credentials: backtraceCredentials,
                                                 dbSettings: BacktraceDatabaseSettings(),
                                                 reportsPerMin: 10,
                                                 allowsAttachingDebugger: false,
                                                 detectOOM: true)
BacktraceClient.shared = try? BacktraceClient(configuration: configuration)

• Objective-C

BacktraceCredentials *credentials = [[BacktraceCredentials alloc]
                                     initWithEndpoint: [NSURL URLWithString: @"https://backtrace.io"]
                                     token: @"token"];

BacktraceClientConfiguration *configuration = [[BacktraceClientConfiguration alloc]
                                               initWithCredentials: credentials
                                               dbSettings: [[BacktraceDatabaseSettings alloc] init]
                                               reportsPerMin: 3
                                               allowsAttachingDebugger: NO
                                               detectOOM: TRUE];

BacktraceClient.shared = [[BacktraceClient alloc] initWithConfiguration: configuration error: nil];

Note on parameters

• initWithCredentials and BacktraceCredentials see here
• dbSettings see here
• reportsPerMin indicates the upper limit of how many reports per minute should be sent to the Backtrace endpoint
• allowsAttachingDebugger if this flag is set to false (Swift) or NO (ObjC) the Backtrace library will not send any reports
• detectOOM indicates if Backtrace will try to detect out of memory crashes and send reports when found. See here for more information on our algorithm works.

Database settings

BacktraceClient allows you to customize the initialization of BacktraceDatabase for local storage of error reports by supplying a BacktraceDatabaseSettings parameter, as follows:

• Swift

let backtraceCredentials = BacktraceCredentials(endpoint: URL(string: "https://backtrace.io")!, token: "token")
let backtraceDatabaseSettings = BacktraceDatabaseSettings()
backtraceDatabaseSettings.maxRecordCount = 1000
backtraceDatabaseSettings.maxDatabaseSize = 10
backtraceDatabaseSettings.retryInterval = 5
backtraceDatabaseSettings.retryLimit = 3
backtraceDatabaseSettings.retryBehaviour = RetryBehaviour.interval
backtraceDatabaseSettings.retryOrder = RetryOder.queue
let backtraceConfiguration = BacktraceClientConfiguration(credentials: backtraceCredentials,
                                                          dbSettings: backtraceDatabaseSettings,
                                                          reportsPerMin: 10)
BacktraceClient.shared = try? BacktraceClient(configuration: backtraceConfiguration)

• Objective-C

BacktraceCredentials *credentials = [[BacktraceCredentials alloc]
                                     initWithEndpoint: [NSURL URLWithString: @"https://backtrace.io"]
                                     token: @"token"];

BacktraceDatabaseSettings *backtraceDatabaseSettings = [[BacktraceDatabaseSettings alloc] init];
backtraceDatabaseSettings.maxRecordCount = 1000;
backtraceDatabaseSettings.maxDatabaseSize = 10;
backtraceDatabaseSettings.retryInterval = 5;
backtraceDatabaseSettings.retryLimit = 3;
backtraceDatabaseSettings.retryBehaviour = RetryBehaviourInterval;
backtraceDatabaseSettings.retryOrder = RetryOderStack;

BacktraceClientConfiguration *configuration = [[BacktraceClientConfiguration alloc]
                                               initWithCredentials: credentials
                                               dbSettings: backtraceDatabaseSettings
                                               reportsPerMin: 3
                                               allowsAttachingDebugger: NO];

BacktraceClient.shared = [[BacktraceClient alloc] initWithConfiguration: configuration error: nil];

PLCrashReporter configuration

BacktraceClient allows to customize the configuration of the PLCrashReporter by injecting its instance.

• Swift

let backtraceCredentials = BacktraceCredentials(endpoint: URL(string: "https://backtrace.io")!, token: "token")
let backtraceConfiguration = BacktraceClientConfiguration(credentials: backtraceCredentials)
BacktraceClient.shared = try? BacktraceClient(
    configuration: backtraceConfiguration,
    crashReporter: BacktraceCrashReporter(config: PLCrashReporterConfig.defaultConfiguration()))
// or
BacktraceClient.shared = try? BacktraceClient(
    configuration: backtraceConfiguration,
    crashReporter: BacktraceCrashReporter(reporter: PLCrashReporter.shared()))

• Objective-C

BacktraceCredentials *credentials = [[BacktraceCredentials alloc]
                                     initWithEndpoint: [NSURL URLWithString: @"https://backtrace.io"]
                                     token: @"token"];

BacktraceClientConfiguration *configuration = [[BacktraceClientConfiguration alloc]
                                                initWithCredentials: credentials];

BacktraceClient.shared = [[BacktraceClient alloc]
                            initWithConfiguration: configuration
                            crashReporter: [[BacktraceCrashReporter alloc] initWithConfig: PLCrashReporterConfig.defaultConfiguration]
                            error: nil];

// or
BacktraceClient.shared = [[BacktraceClient alloc]
                            initWithConfiguration: configuration
                            crashReporter: [[BacktraceCrashReporter alloc] initWithReporter: PLCrashReporter.sharedReporter]
                            error: nil];

Events handling

BacktraceClient allows you to subscribe for events produced before and after sending each report. You have to only attach object which confirm to BacktraceClientDelegate protocol.

• Swift

// assign `self` or any other object as a `BacktraceClientDelegate`
BacktraceClient.shared?.delegate = self

// handle events
func willSend(_ report: BacktraceCrashReport) -> (BacktraceCrashReport)
func willSendRequest(_ request: URLRequest) -> URLRequest
func serverDidFail(_ error: Error)
func serverDidRespond(_ result: BacktraceResult)
func didReachLimit(_ result: BacktraceResult)

• Objective-C

// assign `self` or any other object as a `BacktraceClientDelegate`
BacktraceClient.shared.delegate = self;

//handle events
- (BacktraceReport *) willSend: (BacktraceReport *)report;
- (void) serverDidFail: (NSError *)error;
- (void) serverDidRespond: (BacktraceResult *)result;
- (NSURLRequest *) willSendRequest: (NSURLRequest *)request;
- (void) didReachLimit: (BacktraceResult *)result;

Attaching BacktraceClientDelegate allows you to e.g. modify report before send:

• Swift

func willSend(_ report: BacktraceReport) -> (BacktraceReport) {
    report.attributes["added"] = "just before send"
    return report
}

• Objctive-C

- (BacktraceReport *)willSend:(BacktraceReport *)report {
    NSMutableDictionary *dict = [report.attributes mutableCopy];
    [dict setObject: @"just before send" forKey: @"added"];
    report.attributes = dict;
    return report;
}

Attributes

You can add custom attributes that should be send alongside crash and errors/exceptions:

• Swift

BacktraceClient.shared?.attributes = ["foo": "bar", "testing": true]

• Objective-C

BacktraceClient.shared.attributes = @{@"foo": @"bar", @"testing": YES};

Set attributes are attached to each report. You can specify unique set of attributes for specific report in willSend(_:) method of BacktraceClientDelegate. See events handling for more information.

Attachments

For crash reports/all reports

You can specify file attachments to be sent with every report (including crash reports). File attachments are specified as an Array of URL containing the path to the file.

• Swift

guard let libraryDirectoryUrl = try? FileManager.default.url(
     for: .libraryDirectory, in: .userDomainMask, appropriateFor: nil, create: true) else {
     throw CustomError.runtimeError
}

let fileUrl = libraryDirectoryUrl.appendingPathComponent("sample.txt")

var crashAttachments = Attachments()
crashAttachments.append(fileUrl)

BacktraceClient.shared?.attachments = crashAttachments

• Objective-C

NSString *fileName = @"myCustomFile.txt";
NSURL *libraryUrl = [[[NSFileManager defaultManager] URLsForDirectory:NSLibraryDirectory
         inDomains:NSUserDomainMask] lastObject];
NSURL *fileUrl = [libraryUrl URLByAppendingPathComponent:fileName)];

BacktraceClient.shared.attachments = [NSArray arrayWithObjects:fileUrl, nil];

Per Report

You can also specify per-report file attachments by supplying an array of file paths when sending reports

• Swift

let filePath = Bundle.main.path(forResource: "test", ofType: "txt")!
BacktraceClient.shared?.send(attachmentPaths: [filePath]) { (result) in
    print(result)
}

• Objective-C

NSArray *paths = @[[[NSBundle mainBundle] pathForResource: @"test" ofType: @"txt"]];
[[BacktraceClient shared] sendWithAttachmentPaths:paths completion:^(BacktraceResult * _Nonnull result) {
    NSLog(@"%@", result);
}];

Supplied files are attached for each report. You can specify a unique set of files for specific reports in the willSend(_:) method of BacktraceClientDelegate. See events handling for more information.

Sending an error report

Registered BacktraceClient will be able to send a crash reports. Error report is automatically generated based.

Sending Error/NSError

• Swift

@objc func send(completion: ((BacktraceResult) -> Void))

• Objective-C

 - (void) sendWithCompletion: (void (^)(BacktraceResult * _Nonnull)) completion;

Sending NSException

• Swift

@objc func send(exception: NSException, completion: ((BacktraceResult) -> Void))

• Objective-C

 - (void) sendWithException: NSException completion: (void (^)(BacktraceResult * _Nonnull)) completion;

macOS note

If you want to catch additional exceptions on macOS which are not forwarded by macOS runtime, set NSPrincipalClass to Backtrace.BacktraceCrashExceptionApplication in your Info.plist.

Alternatively, you can set:

• Swift

UserDefaults.standard.register(defaults: ["NSApplicationCrashOnExceptions": true])

• Objective-C

[[NSUserDefaults standardUserDefaults] registerDefaults:@{ @"NSApplicationCrashOnExceptions": @YES }];

but it crashes your app if you don't use @try ... @catch.

Beta functionality

The underlying features are available in BETA. This means they are not covered by the normal Backtrace SLAs.

Breadcrumbs

Breadcrumbs help you track events leading up to your crash, error, or other submitted object.

When breadcrumbs are enabled, any captured breadcrumbs will automatically be attached as a file to your crash, error, or other submitted object (including native crashes) and displayed in the UI in the Breadcrumbs tab.

Enable Breadcrumbs

• Swift

let backtraceCredentials = BacktraceCredentials(endpoint: URL(string: "https://backtrace.io")!, token: "token")
let backtraceConfiguration = BacktraceClientConfiguration(credentials: backtraceCredentials)
backtraceConfiguration.enableBreadCrumbs(breadCrumbTypes: [BacktraceBreadcrumbType.manual, BacktraceBreadcrumbType.log])

• Objective-C

BacktraceCredentials *credentials = [[BacktraceCredentials alloc]
                                     initWithEndpoint: [NSURL URLWithString: @"https://backtrace.io"]
                                     token: @"token"];
BacktraceClientConfiguration *configuration = [[BacktraceClientConfiguration alloc]
                                                initWithCredentials: credentials];
[configuration enableBreadCrumbs:@[@(BacktraceBreadcrumbTypeManual), @(BacktraceBreadcrumbTypeLog)]];

Add Breadcrumbs

• Swift

let attributes = ["My Attribute":"My Attribute Value"]
BacktraceClient.shared?.addBreadcrumb("My Native Breadcrumb",
                                      attributes: attributes,
                                      type: .user,
                                      level: .error)

• Objective-C

NSDictionary *attributes = @{@"My Attribute":@"My Attribute Value"};
[[BacktraceClient shared] addBreadcrumb:@"My Native Breadcrumb"
                                 attributes:attributes
                                       type:BacktraceBreadcrumbTypeUser
                                      level:BacktraceBreadcrumbLevelError];

Error-free metrics

Error free metrics can be used to answer the following questions:

• How many of your unique users (i.e: unique device IDs) using your app are experiencing errors/crashes?
• How many application sessions (i.e: individual application sessions from startup till shutdown/exit) of your app are experiencing errors/crashes?

The web UI allows you to track those metrics at-a-glance as well as in detail (what kinds of errors/crashes are most common?, etc.).

Enable error-free metrics

Once the BacktraceClient is enabled, you can additionally enable error-free metrics like this:

• Swift

BacktraceClient.shared?.metrics.enable(settings: BacktraceMetricsSettings())

• Objective-C

BacktraceMetricsSettings *metricsSettings = [[BacktraceMetricsSettings alloc] init];
[[[BacktraceClient shared] metrics] enableWithSettings: metricsSettings];

FAQ

How does your Out of Memory detection algorithm work?

On the application startup, an oom watcher creates a status file with basic information about the application state. When the application state changes (application goes to background, out of memory warning occurred) the oom watcher updates the application state.

Basic information that we store in the application state file:

• application version
• system version
• is debugger connected?
• application state (foreground vs background)
• report.data - application state when we received a low memory warning
• report attributes - application attributes when we received a low memory warning

When the application status file is not available on application startup it means that user:

• updated backtrace-cocoa library,
• application crash occurred or user closed an application

Below you can find a summary of our algorithm:

On BacktraceOomWatcherInitialization validate if there is the application state file.

• If not, it means this library was updated, a crash occurred or the application was closed - so there is no reason to report out of memory (algorithm exits),
• If the application status does exist, validate if the application was closed by an application update. If the application version is different, then there is no reason to suspect an out of memory (algorithm exits).
• If the application version is the same, validate the system version. If the system version is different, a system update occurred and there is no reason to suspect an out of memory (algorithm exits).
• If both the application version and system version are the same, check if the debugger was connected on the last application session:
  • If the debugger was connected or no report data is available, there is no reason to suspect an out of memory (algorithm exits).
  • If the debugger wasn't connected and report data is available - it means that we were able to capture the application state when low memory warning occurred and probably out of memory exception occured. Report an error.

When sending an error, we include attributes from the application status file so it's clear if this was foreground or background out of memory exception.

Missing dSYM files

Make sure your project is configured to generate the debug symbols:

• Go to your project target's build settings: YourTarget -> Build Settings.
• Search for Debug Information Format.
• Select DWARF with dSYM File.

Finding dSYMs while building project

• Build the project.
• Build products and dSYMs are placed into the Products directory.
• Zip all the dSYM files and upload to Backtrace services (see: Symbolification)

Finding dSYMs while archiving project

• Archive the project.
• dSYMs are placed inside of an .xcarchive of your project.
• Open Xcode -> Window -> Organizer
• Click on archive and select Show in Finder
• Click on Show Package Contents
• Search for dSYMs directory
• Zip all the dSYM files and upload to Backtrace services (see: Symbolification)