Xcode IOS开发一段小代码练习Method and class，输出是空白

OSC有专门的显示代码功能。

#import <Foundation/Foundation.h>   
   
@interface Fraction : NSObject   
-(void) print;   
-(void) setNumerator: (int) n;   
-(void) setDenominator: (int) d;   
@end   
   
@implementation Fraction   
{   
    int numerator;   
    int denominator; 
}
   
-(void) print   
{
    NSLog(@"%i/%i", numerator, denominator);
}   
 
-(void) setNumerator:(int) n
{
    numerator = n;
}   
   
-(void) setDenominator:(int) d;   
{
    denominator = d;
}   
@end   
   
// progame section //   
int main (int argc, char * argv[])   
{   
    @autoreleasepool {   
        Fraction *myFraction;   
   
        // Instance //   
        myFraction = [Fraction alloc];   
        myFraction = [myFraction init];   
   
        // set //   
        [myFraction setNumerator: 1];   
        [myFraction setDenominator: 3];   
   
        // Display //   
        NSLog(@"Fraction is:");   
        [myFraction print];   
    }   
   
    return 0;   
}
 

• 这段代码在我的xcode里面是可以