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I am currently in the process of creating an iOS application, and I was wondering about capitalization of buttons and titles.

For example, should a button say "Add Post" or "Add post".

If I look at ux.stackexchange for example, I see buttons with the form "Ask Question" and "log in".

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marked as duplicate by Charles Wesley, JonW Apr 11 '14 at 15:21

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

up vote 18 down vote accepted

I believe that's a preference thing. The main thing is to be consistent with what you decide.

It could vary on what section of the app you are talking about too. For example, your buttons and titles might be Title Case capitalized, while your links might be lowercase.

Again, just be consistent within the sections that you are standardizing.

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@CharlesWesley - LoL ... they didn't subscribe to the consistency rule did they? – Code Maverick Jan 29 '14 at 4:01
The reason Apple iOS uses a lowercase s for space is because it's not a function button or a call to action, it's a character on the keyboard. The buttons which appear to the right - cancel, search etc - are all functional and so Capitalised. – Harry B Feb 5 '14 at 12:58

The CTA "Add post" is in itself a sentence. The word post is (I'm assuming) not a product name but rather a word like any other word in a sentence and should be treated as such. Using the Title Case should be limited to writing titles, for CTA's (Call To Action) (<-Look, Title Case), you should use Sentence case because that lowers the cognitive load of reading the text.

However, assume that this was a different scenario. And you wanted to know about how to format a label saying "my posts which linked the user to an overview of all her posts. This label is a Title and not a CTA (Since the label doesn't start with a verb). Here it's OK to use the Title Case because it's a practiced convention. Using a Title Case in mere sentences, which also happens to be a CTA labels, is violating the conventional formatting style.

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The label in a button is considered a caption. Thus, style guides have it these need to be capitalised.

Oddly, a few style guides recommend the use of Sentence case rather than Caption Case for captions. See this answer for more.

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Apple as a guideline for that: OS X Human Interface Guidelines

So if you're developing for iOS you probably should read it.

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Character casing your call to action – People generally don’t pay much attention to use proper casing on their button. However, text capitalization makes a noticeable difference in the conversion rate. When your call to action is small like one or two words, like “Sign In” or “Buy Now”, you can use the title case. Since the action word is only one or two words, it needs to be of a commanding nature, and hence the need to use title case on both words. But when you have a call to action that is more than that three to five words, using the sentence case makes the button feel more like a dialogue. All of this serves to make clicking a button more comfortable to the user.

More info -

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From a readability stand point i think Add Post is at a glance more recognizable than Add post or add post.

Avoid ALL CAPS as caps tend to be much more uniform in there width and height character to character making them much harder to read at a glance, where as when you have a mixture you can skim read the word allot easier - this article may also be interesting -

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