App Architecture Series: Building a Better User Interface

October 21, 2019
App Architecture Series: Building a Better User Interface

At Michi¬≠gan Soft¬≠ware Labs, we don‚Äôt sim¬≠ply write code to sat¬≠is¬≠fy require¬≠ments. We find ways to solve prob¬≠lems effi¬≠cient¬≠ly and effec¬≠tive¬≠ly. Know¬≠ing that a well-struc¬≠tured appli¬≠ca¬≠tion comes down to a set of tech¬≠niques and pat¬≠terns, I have been explor¬≠ing design pat¬≠tern the¬≠o¬≠ries and how they shape our think¬≠ing. Grant¬≠ed, it‚Äôs huge and com¬≠plex top¬≠ic, but here are some areas I‚Äôd like to cover: 

  • Con¬≠sis¬≠ten¬≠cy
  • Reusabil¬≠i¬≠ty
  • Opti¬≠miza¬≠tion
  • Testa¬≠bil¬≠i¬≠ty

Let‚Äôs begin with the pre¬≠sen¬≠ta¬≠tion lay¬≠er. The user inter¬≠face (UI) is the top-most lev¬≠el of the appli¬≠ca¬≠tion. It‚Äôs also the most frag¬≠ile aspect of the devel¬≠op¬≠ment process‚ÄČ‚ÄĒ‚ÄČthe part clients want to tweak long after we begin imple¬≠ment¬≠ing code. 

A senior devel¬≠op¬≠er once told me he nev¬≠er want¬≠ed to devel¬≠op mobile apps because of the con¬≠stant UI headaches. The ongo¬≠ing changes drove him nuts. I on the oth¬≠er hand enjoy changes, because they lead to progress. The ques¬≠tion is, how can we bet¬≠ter pre¬≠pare for these inevitable changes? 

The tra¬≠di¬≠tion¬≠al cod¬≠ing work¬≠flow looks some¬≠thing like this: Get the mocks from design¬≠ers, open a new sto¬≠ry¬≠board in Xcode (or cre¬≠ate a new xml file in android stu¬≠dio), fol¬≠low the design details close¬≠ly (font size, text and back¬≠ground col¬≠or, etc.), build¬≠ing every com¬≠po¬≠nent one by one (text fields, labels, but¬≠tons, views, shapes, etc.). 

A num¬≠ber of ele¬≠ments are repeat¬≠ed when writ¬≠ing UI code. Things like text size, font styles, mar¬≠gins, paddings, and col¬≠ors. They tend to be so sim¬≠ple I don‚Äôt pay much atten¬≠tion to what I‚Äôm doing. With text col¬≠or, for exam¬≠ple, I just grab the hex val¬≠ue from the Zeplin file and code: 

self.label.textColor = UIColor(red:0.09, green:0.40, blue:0.01, alpha:1.0)

Not ide¬≠al, right? These val¬≠ues don‚Äôt make much sense and are error prone. Lat¬≠er, I changed them to: 

self.label.textColor =

An improve¬≠ment, but still not good enough. Nam¬≠ing can be tricky. What if I want to go from green to pur¬≠ple? I talked to our design¬≠ers and we came up with a bet¬≠ter col¬≠or nam¬≠ing sys¬≠tem that defines pri¬≠ma¬≠ry col¬≠ors, sec¬≠ondary col¬≠ors, error col¬≠ors, etc. As it turns out, a small change in col¬≠or nam¬≠ing pro¬≠vides far greater flex¬≠i¬≠bil¬≠i¬≠ty down the road, espe¬≠cial¬≠ly if there‚Äôs a theme switch requirement. 

This exam¬≠ple under¬≠lies the impor¬≠tance of open com¬≠mu¬≠ni¬≠ca¬≠tion between devel¬≠op¬≠ment and design teams. Col¬≠lab¬≠o¬≠ra¬≠tion is a must if we want to be able to reuse/‚Äčmaintain the resources ref¬≠er¬≠ences in the code. 

Start With a Style Guide or Design System?

As the chart, below, shows, Style Guide is a set of design basics. Here, you can find every¬≠thing from col¬≠ors, typog¬≠ra¬≠phy to grids and paddings. This is the most abstract part of UI design sys¬≠tem. For small projects, it should be all you need. 

The Design Sys¬≠tem on the oth¬≠er hand is more com¬≠pli¬≠cat¬≠ed and requires more of a team effort. It‚Äôs noth¬≠ing new. In fact, many com¬≠pa¬≠nies are already using it: ‚Äč‚ÄúA Design Sys¬≠tem is the sin¬≠gle source of truth which groups all the ele¬≠ments that will allow the teams to design, real¬≠ize and devel¬≠op a product.‚ÄĚ 

When we take a clos¬≠er look, it‚Äôs actu¬≠al¬≠ly a com¬≠po¬≠nent-based sys¬≠tem that ensures visu¬≠al and func¬≠tion¬≠al con¬≠sis¬≠ten¬≠cy. This includes all the com¬≠po¬≠nents of the Style Guide along with an inte¬≠grat¬≠ed set of func¬≠tion¬≠al com¬≠po¬≠nents, such as spin¬≠ners, but¬≠tons, images, etc. Although com¬≠pa¬≠nies have unique ways of defin¬≠ing a Design Sys¬≠tem, the end goal is con¬≠sis¬≠ten¬≠cy and reusability. 


Con¬≠sis¬≠ten¬≠cy can elim¬≠i¬≠nate con¬≠fu¬≠sion and short¬≠en the learn¬≠ing curve for users. Con¬≠sis¬≠tent and clear com¬≠mu¬≠ni¬≠ca¬≠tion also ensures a lev¬≠el of qual¬≠i¬≠ty con¬≠trol when ques¬≠tions arise around use case, such as: What load¬≠ing indi¬≠ca¬≠tor should we use to inform users the data is being loaded, a sys¬≠tem spin¬≠ner or a fan¬≠cy skele¬≠ton view? How should we dis¬≠play an error mes¬≠sage if one should occur? Should users be expect¬≠ed to pull and refresh to search or should we show them a retry but¬≠ton? These aren‚Äôt always indi¬≠cat¬≠ed in the design file, so devel¬≠op¬≠ers often leave them blank. 

Anoth¬≠er issue is con¬≠sis¬≠ten¬≠cy across plat¬≠forms. Most of the time we build apps for both Android and iOS. Google and Apple guide¬≠lines rec¬≠om¬≠mend using plat¬≠form-stan¬≠dard con¬≠trols when¬≠ev¬≠er pos¬≠si¬≠ble. Unfor¬≠tu¬≠nate¬≠ly, Google and Apple have very dif¬≠fer¬≠ent thoughts on the UX with their devices and apps. Google tends to go deep, while Apple is flat. 

Should we cre¬≠ate a sep¬≠a¬≠rate design style for each plat¬≠form to give users a ‚Äč‚Äúnative‚ÄĚ expe¬≠ri¬≠ence and main¬≠tain con¬≠sis¬≠ten¬≠cy with oth¬≠er mobile apps with¬≠in each platform‚Äôs ecosys¬≠tem? Or should we keep the plat¬≠forms iden¬≠ti¬≠cal to main¬≠tain a con¬≠sis¬≠tent UI expe¬≠ri¬≠ence for users, regard¬≠less of who they are or what device they‚Äôre on? 

Ulti¬≠mate¬≠ly, these are design or even busi¬≠ness deci¬≠sions; how¬≠ev¬≠er, from a developer‚Äôs per¬≠spec¬≠tive it is obvi¬≠ous that build¬≠ing native components/‚Äčnavigation pat¬≠terns is more effi¬≠cient than build¬≠ing a mix of Google‚Äôs Mate¬≠r¬≠i¬≠al Design com¬≠po¬≠nents and Apple‚Äôs Human Inter¬≠face Guidelines. 

Before cod¬≠ing your first ele¬≠ment, it‚Äôs always a good idea to eval¬≠u¬≠ate the design‚Äôs con¬≠sis¬≠ten¬≠cy with the native sys¬≠tem to deter¬≠mine how much effort will go into build¬≠ing cus¬≠tom ele¬≠ments, such as: 

  • Nav¬≠i¬≠ga¬≠tion pat¬≠terns and nav¬≠i¬≠ga¬≠tion elements
  • Default con¬≠trols
  • Inputs styles and but¬≠ton styles
  • Alerts
  • Typog¬≠ra¬≠phy
  • Ani¬≠ma¬≠tion

List¬≠ing and com¬≠par¬≠ing these ele¬≠ments gives a bet¬≠ter sense of how to approach the project. For instance, whether to use native com¬≠po¬≠nents or exist¬≠ing com¬≠po¬≠nents, or whether to cre¬≠ate com¬≠pound com¬≠po¬≠nents or self-drawn com¬≠po¬≠nents. A view may seem basic enough but actu¬≠al¬≠ly con¬≠tain many self-drawn or com¬≠pound com¬≠po¬≠nents. This is when we begin to under¬≠es¬≠ti¬≠mate the amount of effort involved.


It‚Äôs a tall order writ¬≠ing code that can be uti¬≠lized through the dura¬≠tion of a project. By its nature devel¬≠op¬≠ment is an evolv¬≠ing process, requir¬≠ing mod¬≠i¬≠fi¬≠ca¬≠tions as new fea¬≠tures are added or sys¬≠tems upgrad¬≠ed. One thing we need to pay atten¬≠tion to is when we intend to cre¬≠ate a component/‚Äčstyle glob¬≠al¬≠ly, but end up instead with a series of over¬≠ride base class¬≠es or xml styles to fit spe¬≠cif¬≠ic require¬≠ments. Such over¬≠rides erode consistency. 

Some¬≠thing else to keep in mind are the dif¬≠fer¬≠ences between plat¬≠forms. It‚Äôs impor¬≠tant to know how UI sys¬≠tems are struc¬≠tured in order to deter¬≠mine the best strate¬≠gies for work¬≠ing with each one. 

And we haven‚Äôt even begun to touch on Opti¬≠miza¬≠tion and Testa¬≠bil¬≠i¬≠ty. Look for that in our fol¬≠low up post. 

To be continued…

Mei Huang
Mei Huang
Software Developer

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