I've got some issues with the new autocomplete of Xcode 7.3
When I import a class, the class won't show up in autocomplete. Even more annoying, when an imported class contains a typedef NS_ENUM, the possible values won't show up either. In both cases, when I manually enter the class name or enum value, that perticular value will show up the next time, but for the possible enum values, all other values still won't show.
Further, I've noticed the autocomplete isn't ordered (alphabetically) anymore.. So, for example, when I've got a class with initializers in the .h file:
-(instancetype)initWithServiceName:(NSString*)serviceName listenPort:(NSUInteger)listenPort keys:(NSArray*)keys;
-(instancetype)initWithServiceName:(NSString*)serviceName listenPort:(NSUInteger)listenPort keyFile:(NSString*)keyFile;
when I start typing "-(instancetype)init" in the .m file, the autocomplete will show the first initializer, followed by about 14 autocompletions that doesn't even relate to it by far and then (finally) the second initializer...
Is there a way to use 7.3 (or at least the SDKs within it) but switch back to the old (but very lovely, and working) autocomplete feature from 7.2?
I had this problem myself and after looking through all the other similar questions & answers about this, I couldn't find a solution. However, I finally found what worked for me.
Go to Xcode -> Preferences -> Components. There you will probably find a screen that looks like the following:
This shows that the documentation has not has not been downloaded and therefore, any attempts to re-index or re-build the application without downloading the documentation would prevent you from being able to use the autocompletion functionality.
Once I downloaded the Xcode 7.3 Documentation and the OSX 10.11.4 Documentation, this was enough for me to get the autocomplete functionality back (I was trying to build an OS X app, so feel free to download as much documentation as is relevant for you).
I med this problem, go to XCode -> Preferences -> Text Editing, cancel Enable type-over completions .
this will also happen when you create a new file ,then the new file will lose the autocomplete ability.
Click cmd+shift+k trying cleaning the project and building it,
If that doesn't work, delete derived data from /Users//Library/Developer/Xcode/DerivedData
Or delete at here :
Autocomplete will be back ok 🎉!
try cleaning the project and building it, if that doesn't work, delete derived data from /Users//Library/Developer/Xcode/DerivedData, and then try it again. should work
I was having huge problems after upgrading from 7.2 to 7.3 and it completely ruined my productivity. But after I deleted all derived data, completely quit XCode, and then rebooted my system, everything went back to normal. Life is good again...
来源：https://stackoverflow.com/questions/36242732/xcode-7-3-autocomplete-issues