ios - Are NSString and NSData the only types I can insert into KeyChain? -

you can convert integer nsstring or array nsdata , insert them ios keychain.

my question is: it? or there direct way insert double, float or boolean?

you can store primitive types in form of nsnumber , save them keychain. has methods like: numberwithbool:, numberwithinteger:, numberwithfloat:.

here , here examples of storing bool in keychain.