Designing a mobile app Chris Greenhalgh G54UBI / Chris Greenhalgh

First… Work out what the application is meant to do, e.g. – Identify possible users and situations of use – Identify use cases, i.e. main activities – Write one or more user stories 2Chris Greenhalgh

Example: tree walk Chris Greenhalgh Existing paper walking guide to trees and gardens on the University Park campus (as used for GLF)

Example: user story Ali is visiting University Park and installs the tree walk app on her Android phone She starts the app and the main view shows the walking map As she explores the area the app chimes and pops up more detail of nearby points of interest She reads these with interest before continuing her walk Chris Greenhalgh

D1. Identify application “screens” Work out how the application will be divided into screens, e.g. – Splash screen – Map overview – Location detail view – Help – … 5Chris Greenhalgh

D1: Example Welcome screen Main map screen Point of interest screens – 4: Acer saccharinum; 5: Ulmus ‘Sapporo Autumn Gold’; 7: Metasequoia glyptostroboides Where am I? screen (native app) Help screen Chris Greenhalgh

Non-GUI apps “Screens” are most relevant for GUI-based apps, but still a necessary starting point for other apps, e.g. audio For non-GUI apps there may be other application “modes” which effectively sub-divide/specialise each screen – E.g. “seeking”, “detail”, … These should be identified and charted in the same way as screens 7Chris Greenhalgh

D2. Define screen “flow” Work out how the application moves from one screen to another, e.g. – On direct user input (e.g. a button) – On “back” – On timer – On sensor input condition 8Chris Greenhalgh

D2: Example Chris Greenhalgh Welcome Main (map) Where? Detail (1) Help Back “Start” button “Help” button “Where?” button GPS trigger

D3. “wireframe” each screen For each screen, work out what GUI elements will make it up and roughly how they will be laid out, e.g. – Images, Text, Buttons, Gauges, … Specify what each GUI element will do Highlight any elements that change – These may be domain model objects or properties! (see 6) 10Chris Greenhalgh

D3: Example WelcomeMain Chris Greenhalgh Welcome to the University Park tree walk Start Help Where am I? GPS:

D3: Example HelpMap (native app) Chris Greenhalgh OK Blah blah blah blah Tree Walk Help

D3: Example Detail 4… Chris Greenhalgh OK On the right hand side of the drive is a group of young Acer saccharinum, the Silver maple, introduced from Eastern North America in It is a fast growing tree. 4: Silver Maple

D4. Specify sensor input and effects Identify – Which sensors are monitored – When, e.g. on which screens – How sensor input is processed E.g. identify region entry – Which screen elements are affected and how E.g. signal strength, user position – What other actions result E.g. screen transitions 14Chris Greenhalgh

D4: Example Sensor is GPS Only required on main screen Accuracy is shown on main screen GPS gauge Position is checked against interest regions Entering interest region switches to detail screen Chris Greenhalgh

D5. Specify any “invisible” activities E.g. – Network operations – Audio / sound effects – Background processing 16Chris Greenhalgh

D5: Example Transition to detail view accompanied by “chime” sound-effect Chris Greenhalgh

Optional: D6. Define/Refine the domain model Identify the classes of “things” that your application “knows” about, e.g. – Trees, shops, exhibits, places, … Identify what your application “knows” about each “thing”, i.e. – the properties and relationships that are shown to the user (see 3) – The properties and relationships that are used internally when deciding what to do (see 2, 4, 5) This activity can be done and re-done at any stage through the design and refinement process 18Chris Greenhalgh

Why D6? Aim to separate – Code = behaviour – Screen and element “templates” = appearance – Domain data = data values = specific content Because – Code is harder to change – Specific content can be represented more concisely as data values – Specific content can be changed more easily Potentially dynamically, e.g. from a server 19Chris Greenhalgh

D6: Example Chris Greenhalgh “Things” are “points of interest” – Or perhaps more specifically “trees” A point of interest has: – A spatial trigger region – A map key (e.g. “4”) – “Detail” information A title Some descriptive text

Iterate… Review and refine taking account of – Walkthroughs – Details emerging from later stages – Other use cases – Paper prototyping – Implementation constraints – User tests Chris Greenhalgh

Summary D1. Identify application “screens” D2. Define screen “flow” D3. “wireframe” each screen D4. Specify sensor input and effects D5. Specify any “invisible” activities D6. Define/Refine the domain model (optional) Chris Greenhalgh