Converting upper-case string into title-case using Ruby

If you’re using Rails (really all you need is ActiveSupport, which is part of Rails), you can use titleize:

"MY STRING HERE".titleize
# => "My String Here"

If you’re using plain Ruby but don’t mind loading a small amount of ActiveSupport you can require it first:

require 'active_support/core_ext/string/inflections'
# => true
"MY STRING HERE".titleize
# => "My String Here"

N.B. By default titleize doesn’t handle acronyms well and will split camelCaseStrings into separate words. This may or may not be desirable:

"Always use SSL on your iPhone".titleize
# => "Always Use Ssl On Your I Phone"

You can (partially) address this by adding “acronyms”:

require 'active_support/core_ext/string/inflections' # If not using Rails
ActiveSupport::Inflector.inflections do |inflect|
  inflect.acronym 'SSL'
  inflect.acronym 'iPhone'
end
"Always use SSL on your iPhone".titleize
# => "Always Use SSL On Your IPhone"

For those who speak the Queen’s English (or who struggle to spell titleize), there’s no .titleise alias but you can use .titlecase instead.