iOS 5: Make NSString Category include NSCFConstantString?

Question

I have an NSString category class (NSString+URLEncoding.h). I am running into and unknown selector crash, because the string I am calling the categ

Answer 1

Just spent 30 minutes figuring out exactly the same issue. After fiddling with linker I found out that the category wasn't present in Compile Sources list in my target's Build Phases. Be sure to check it's there.

Answer 2

There's an issue with the linker that can cause its dead-code stripping to completely omit any object files that only contain obj-c categories (or that are otherwise unreferenced). Theoretically passing the -ObjC flag to the linker should fix this, but that doesn't seem to always work. You can work around this issue by providing the -all_load linker flag, which will cause the linker to always link in all object files.

Note that you might have to set -all_load on the parent project if your category is part of a sub-project or library that you-re including somewhere.

Update: I believe -ObjC is reliable now and has been for years so you can stop using -all_load for this issue.

Answer 3

__NSCFConstantString is a subclass of NSString, so any categories on NSString apply to __NSCFConstantString too.

Either you're not linking in your category, or your category doesn't define a URLEncodedString method in its @implementation.