SQLiteConnectionNative.m : getBytesWithEncoding and stringWithCharacters not exists in NSString

Xcode 9.3 with iOS 11.3

Getting four ARC Semantic issues error in SQLiteConnectionNative.m

1. Line No.: 166,285
   IOSByteArray *sql = [sqlString getBytesWithEncoding:NSUTF16StringEncoding];

Error : No visible @interface for 'NSString' declares the selector 'getBytesWithEncoding:'

2. Line No.: 235, 535 :

return [NSString stringWithCharacters:chars];
Error : No known class method for selector 'stringWithCharacters:'

Please help me on this.