[Objective-C] Permission control in OC

1: The scope of the default instance variable is: this class body. The default inherited instance variables can be used directly. 2: Permission control symbol for instance variables 3: projected by default 4: only single inheritance is supported in oc 5: Put the common things in the parent class, and the personal things in the Child class Modifier Class Subclass Anywhere Private Yes     Projected Yes Yes Yes Public Yes Yes Yes The following uses the inheritance relationship of the car to demonstrate the default permission (protected)   I. Car. h   //// Car. h // Car /// Created by hmjiangqq on 14-1-22. // Copyright (c) 2014 hmjiangqq. all rights reserved. // # import @ Interface Car: NSObject {@ protected // default permission int cID; // id float speed; // speed NSString * name; // name}-(void) run; @ end Ii. Car. m //// Car. m // Car /// Created by hmjiangqq on 14-1-22. // Copyright (c) 2014 hmjiangqq. all rights reserved. // # import "Car. h "@ implementation Car // instantiate the attributes of a Car-(id) init {if (self = [super init]) {cID = 1000; speed = 120; name = @ "";} return self;}-(void) run {NSLog (@ "start... ");} @ end Iii. BMW. h /// BMW. h // Car /// Created by hmjiangqq on 14-1-22. // Copyright (c) 2014 hmjiangqq. all rights reserved. // # import "Car. h "@ interface BMW: Car @ end 4. BMW. m /// BMW. m // Car /// Created by hmjiangqq on 14-1-22. // Copyright (c) 2014 hmjiangqq. all rights reserved. // # import "BMW. h "@ implementation BMW-(void) run {name = @" BMW "; NSLog (@" car name is % @ \ n ", name);} @ end Main. m //// Main. m // Car /// Created by hmjiangqq on 14-1-22. // Copyright (c) 2014 hmjiangqq. all rights reserved. // # import # Import "Car. h "# import" BMW. h "int main (int argc, const char * argv []) {@ autoreleasepool {// insert code here... NSLog (@ "Hello, World! "); Car * car = [[Car alloc] init]; [car run]; BMW * bmw = [[BMW alloc] init]; [bmw run];} return 0 ;}