iphone - Objective-C hidden instance variables -

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hi i've seen 2 ways declare hidden instance variables in .m file 1)

@interface myclass()  {   //my ivars } @end @implementation myclass   //my implementation @end 

2)

@implementation myclass {  //my ivars }  //my implementation @end 

confused difference between two, and/or coding conventions when comes this. help!

good question! tend see instance variables declared in interface, implementation works too. thoughts on issue:

1. i think using interface better practice
2. i think ivars declared in implementation inaccessible subclasses