John Wittnebel

240-***-**** I adfe3d@r.postjobfree.com

* *****’ Experience in Information Technology and iOS Mobile Development

PROFESSIONAL PROFILE

●Extensive experience and with iOS application development using iOS SDK, Xcode, Objective-C, Swift, CocoaTouch, Storyboards, Interface Builder, and various other tools.

●Comfortable working with and adding 3rd-party dependencies to projects for specialized functionality, such as Alamofire, through CocoaPods.

●Strong knowledge of Objective-C (iPhone/iPad), iOS SDK 13, iOS SDK 12, iOS SDK 11, iOS 11.x, C++.

●Adept in the use and understanding of UIKit, XCTest, NSCoding, NSUserDefaults, SQLite, and other tools & frameworks.

●Experience with Agile/Scrum, Test-Driven Development (TDD), and other software development methodologies.

●Knowledgeable of MVC, MVVM, Delegation & Protocols, Notifications, KVO & KVC, Singleton, Decorator, and other OOP design patterns.

●Comfortable constructing UIs through Storyboards or programmatic UI statements with the use of Size Classes and AutoLayout constraints to allow for dynamic adjustment for different screen sizes.

●Experienced working with multithreading through GCD and NSOperations to execute tasks on background threads in order to free up and improve upon the user’s experience, UI/UX.

●Seasoned in the consummation of RESTful web services and parsing services responses using NSJSONSerialization and SwiftyJSON for JSON data, and NSXMLParser for XML.

●Knowledgeable in various architectures, such as Model View Controller and Model View ViewModel (MVVM).

●Well versed in other programming languages beyond iOS development, such as C++, Python, JavaScript, and Lua.

●Experience in creating applications that support all orientations on iPhone and iPad.

●Advanced experience in Testing and Bug-Fixing using XCTest framework, Breakpoints, LLDB statements, NSLog statements, and Instruments.

●Experience working in multicultural Agile Scrum environments with both local and remote teams.

●Skilled in asynchronous HTTP and HTTPS requests using a variety of tools such as GCD, NSOperations, NSURLSession, and AFNetworking.

●Published iOS iPhone/iPad apps in the App Store and managed the app in the Apple approval process from beginning to end.

●Skilled developer with over 5 years of experience implementing and deploying native and cross-platform iOS applications. Able to learn and adapt to new frameworks and APIs with ease. Proficient with Objective-C, Swift as well as many Apple and 3rd-party frameworks. Curious about new technology and languages.

●Passionate about developing, designing, improving, enhancing, and even maintaining world class iOS-based apps across multiple platforms (iPhone, iPad, etc.).

TECHNICAL SUMMARY

Coding Languages: Swift, Objective-C, C++, Python, Assembly, Java, JavaScript, Lua, MATLAB, R, Maple

IDEs: Xcode 8-11, IntelliJ, Visual Studio

Mobile OS: iOS

Databases: CoreData, Realm, SQLite, mySQL, Data Modeling, RDBMS, Query Languages, Schema Normalization

Native Frameworks and Libraries: UIKit, CocoaTouch, CoreData, CoreGraphics, MapKit, CoreLocation, XCTest

Third-Party Package Managers: CocoaPods, Firebase

Native Services: URLSession, JSONSerialization, Reachability, Apple Push Notification (APNS), UserDefaults, NotificationCenter, OperationQueue, MessageUI, AddressBook

Web Services: RESTful API, JSON, XML, Alamofire

General: MVC, MVVM, Delegation & Protocols, Notifications, KVO & KVC, Decorator, Singleton, Adapter, Categories/Extensions, JIRA, Push Notifications, OOP, Web APIs

Operating Systems: MacOS, Ubuntu, Archlinux, Microsoft Windows

Servers: SQL Server 2016, Windows Server

Computer Operations: SAP, Microsoft Office 2013, Microsoft Office 2016/Office 365

Agile: Scrum, Pair Programming, Test-Driven Development, Dynamic Systems Development

UI: Auto Layout, Adaptive Layout, Storyboard, Interface Builder, Size Classes, MapKit, UIKit, UIView

Testing: TDD, Unit Testing, XCTest, Automated Testing

Version Control: Git, GitHub, SourceTree, BitBucket

Continuous Integration: Hudson, Jenkins

Dependency Injection: Setter, Interface, Constructor

Marriott International / Bethesda, Maryland

Senior iOS Developer, Jan 2018 – Present

https://itunes.apple.com/us/app/marriott-international/id455004730

●iOS app development was implemented using XCode, CocoaPods, Interface Builder, and Instruments with Swift.

●Worked on geolocation services and map services to display directions around users using MapKit, GoogleAPI, and CoreLocation.

●Implemented additional custom behavior in maps by leveraging MapKit framework.

●Alamofire used for consuming various RESTful API services, to make connections to server, and handle authentication challenges.

●Regularly performed code reviews to ensure efficiency, readability, and maintainability.

●Oversaw a team of developers, assigning tasks and assisting in introducing new employees to the code base.

●Performed JSON serialization using Codable after consuming RESTful endpoints

●Used Git for source control, pushing changes to company repository on GitHub.

●Took part in full Software Development Life Cycle of multiple applications from concept to production.

●Created models in MVVM and worked on delegates and architecture for updating views and user information.

●Utilized Keychain for secure offline persistence while adhering to HIPAA regulations.

●Delegation, NSNotifications, Singleton, and several other patterns used to better create the app and simultaneously satisfy the key non-functional requirements of scalability and maintainability.

●Performed all roles from UI design to writing code.

●Responsible for defining technical evaluation criteria for product and technology selection and determining technical approaches to ensure all architectural solutions result in a coherent systems design.

●Profiled the application extensively using Instruments to improve performance throughout multiple sprints.

●Worked with JIRA for story, task, and bug tracking.

●Developed UI sizes and orientations using Storyboard and Auto Layout features necessary for mobile app to display correctly on various mobile screen.

●Performed to complete unit testing, integration testing and regression testing the application.

●Profiled the application extensively using Instruments to improve performance throughout multiple sprints.

●Agile/SCRUM methodology with one-week sprints.

●Designing, developing, testing, and implementation of app in App Store.

Allegiant Travel Company / Las Vegas, Nevada

Senior iOS Developer, Jan 2017 - Jan 2018

https://itunes.apple.com/app/id528413490

●Migrated code base over to Swift from Objective-C.

●Worked with design team to design and architect new features and functionality such as the card timeline for keeping track of your itinerary and manage your trip.

●UI developed using Storyboards with AutoLayout constraints, UI/UX targeted towards both iPhone and iPad supported devices.

●Worked on various feature implementations and enhancements throughout the app to improve the user experience and usability.

●Resolved various issues and bugs by debugging and utilizing NSLog statements, breakpoints, LLDB statements, and crash logs.

●Jenkins utilized for Continuous Integration.

●Utilized Instruments, Crash Logs, LLDB statements, NSLog statements, GDB/LLDB, and Breakpoints to resolve various issues and bugs brought to attention by QA team.

●Fixed memory issues by using Instruments, most notably using the Allocations and Time Profiler tools.

●Utilized GCD/NSOperation multithreading techniques for better performance.

●Used Jenkins with Git for continuous integration.

●Maintained application by fixing bugs, and responding to client issues and requests.

●Utilized NSOperations for downloading images on background thread so as to not lock up the UI and provide a better user experience.

●Used NSCache to enable caching workflow for images to reduce loading time from the initial launch of app onwards.

●Design patterns used: MVVM, Delegation, Singleton, Extensions, Notifications, KVO.

●Profiled the application extensively using Instruments to improve performance throughout multiple sprints.

●All web communications are performed in background threads to enhance performance and the user experience.

●Agile/SCRUM methodology utilized on project with three-week sprints and daily scrums.

●Designing, developing, testing and implementation of app in App Store.

Volaris / Los Angeles, California

iOS Developer, Sept 2015 - Jan 2017

https://itunes.apple.com/app/id945390888

●Developed iOS app using XCode, CocoaPods, Interface Builder, and Instruments with Swift.

●Reviewed and refactored code and transitioned code base from Objective-C to Swift.

●Did REST calls using AFNetworking in order to communicate to APIs, and then parsed JSON responses using NSJSONSerialization.

●Worked extensively on UICollectionView and made customized UITableViewCells per the client’s requirements. Pre-fetching data for different views for smooth screen transition.

●Agile/SCRUM methodology utilized on project with three-week sprints.

●Worked in a Test-Driven Development (TDD) environment using Continuous Integration and working with a QA team.

●Created test cases to streamline and optimize code with XCTest.

●Worked with Storyboards, Size Classes and AutoLayout constraints for graceful orientation-handling and dynamically sized views to support for various iPhone and iPad devices.

●Offered several design elements that added value to the application and improved the UX.

●Implemented UI using a combination of Storyboard and Programmatic UI components.

●Redesigned and engineered mobile agility process with high use of current technology, systems and existing organization assets.

●Documented design and code-based decisions.

●Used GCD (Grand Central Dispatch) along with Alamofire for asynchronously downloading and presenting images without interrupting the user experience.

●Met with business leaders and stakeholders to help determine requirements.

Ahasay IT Consulting SPRL / New York City, New York

Jr. iOS Developer, June 2012 - Sept 2015

https://itunes.apple.com/app/id861506097

●Followed a work data flow principle for design and development.

●Used Cocoa frameworks such as UIKit and CocoaTouch.

●Designed and created UI and Application flow using UIKit.

●Worked on UI navigation and improvement of user experience (UX).

●Tested the app on simulators and actual devices to assure quality and performance.

●Agile/SCRUM methodology utilized on project with two-week sprints.

●Employed UIControl, UIResponder, etc, and various action and delegate methods.

●Core Data used to persist user data and to prepopulate UITextFields with persisted data from prior access.

●Used MVC architecture to have the UI update reactively to data model changes.

●Performed regular testing of application along with development, using XCTest.

●Fixed memory and performance issues by using Instruments, most notably using the Allocations and Time Profiler tools.

●Participated in review meetings and took the initiative to meet the QA testing targets.

●Responsible for managing the work log and following the schedule to ensure the iOS app team completed projects before deadline.

EDUCATION

University of Waterloo

Master of Mathematics in Computer Science, specializing in Algorithms and Complexity

University of Waterloo

Bachelor of Mathematics in Computer Science, Minor in Pure Mathematics

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