Some of the docs I've had to deal with lately, that I've found very useful and easy to navigate: https://apidocs.mailchimp.com https://dashboard.batch.com/doc [Requires Login] (Great product for marketing push notifications, by the way) Also Apple has a great doc site. Very verbose, but thorough: https://developer.apple.com/library/ios/documentation/UIKit/...
Thanks karmy, this is super useful.