iOS 3

.h .c ==C; .h .cpp == C++ .h .m ==oc; oc& c++ ==.h&&.mm; XYZPerson.h:

@interface XYZPerson : NSObject
-(void)sayHello;
@end

XYZPerson.m

#import "XYZPerson.h"
@implementation XYZPerson
-(void)sayHello{
  NSLog(@"Hello, World");
}
@end

iPhone 屏幕: 3GS 3.5 320480 @1x 4/4s 3.5 320480 @2x 640960 5/5c/5s 4.0 320568 @2x 6401136 6 4.7 375667 @2x 7501344 6Plus 5.5 414*7356 @3x 12422208 UIView,UILabel,UIImage,UIImageView.