What is a double in xcode?

What are some Xcode tips and tricks that can make iOS and Mac developers more productive?

• When you're new to Xcode, you see all these features, but since there's so much to learn, you kind of put them aside and forget about them. Out of all the "advanced" Xcode features, which ones do you find most useful?

• Answer:

  In order of most useful. Many of these tips are fairly basic, but often ignored: Open a file directly COMMAND + SHIFT + O It's super fast, and smart about camel case. You can search "NearbyFriends", and it'll bring up results like NearbyBlahFriends.h . Switch between header and .m/.mm file CONTROL + COMMAND + UP (or DOWN) arrow. This is more useful than the "counterparts" view, since it is quick and frees up the right side for like the Comparison panel, etc. When used in conjunction with counterparts, it has the effect of swapping panes, which makes sense and is awesome. Go back or forward in your file history CONTROL + COMMAND + LEFT / RIGHT arrow. This is quicker than mouse swipes: it'll save you from carpal tunnel, and there's no animation. "Recent files" Seeing where a particular function is called Put your cursor on a function name, and see the callers menu. Search and Filter Sometimes you're looking for a string in some UI, like "Done", and you naively type that into the search panel. You get like 1000 results. You do remember, however, that the file name has the word "Nearby" in it. Type that into the filter at the bottom, it's quick! Limit issues in the Issue Navigator to only Errors Depending on the current state of your overall code base (and Xcode's hormonal imbalance at the moment), the issue navigator can easily get slammed with warnings. Turn that exclamation point button on to see the errors. Refactoring Tools Select some code in a method, and go into this menu: This is incredibly slow for me given our gigantic code base, so I only use it for very large refactors, but if you're working on a newer project, it could be useful for you. Extract will take some highlighted code in a method, and extract it into a newer method, properly passing and declaring the necessary arguments to the new method. Rename will rename symbols, update references to them, and where applicable, change file names along with file names in #import header statements. Those are the most useful actions in the Refactor sub-menu, and I dearly miss this ability from my Java / Eclipse days. The following are useful if and only if you are using git... Comparison View Very useful, especially before you do a commit, and send it off for review. Viewing history in Comparison View This is between the two panes in comparison view. You click that history icon at the bottom, then you can move the left and right arrow carets up and down. "Show only files with source control status" This is especially useful when you are about to do a commit, and want to quickly review your changes. Use this in conjunction with the Comparison view. Select the "Project Navigator" tab in the left side bar and hit that button (shown in blue in the screenshot). Blame View Beyond knowing who touched which line last, what's also great is that if there are links in the commit description, they're clickable! This is very useful at Facebook, given our workflows with our code review system ( http://phabricator.org/ ). Note that the screenshots shown are minimal since I didn't want to leak any Facebook source code, which is all I have handy ATM. :-) . See also my answer on 3rd party tools for iOS devs: