commond版的obj-c helloworld

xcode4.2

建项目的时候要选 foundation，不然没有Foundation包

 

注意看，这里不在需要手动写setUserName

要得到属性值的话，用self.****

main.m

#import <Foundation/Foundation.h>
#import "Fraction.h"

int main (int argc, const char * argv[])
{

    @autoreleasepool {
        
        // insert code here...
        //NSLog(@"Hello, World!");
        // insert code here...
        printf("Hello, World!\n");
        
        Fraction *frac = [[Fraction alloc] init];
        // set the values
        [frac setUserName: @"mahone"];
        //[frac setDenominator: 3];
        // print it
        printf( "The fraction is: " );
        [frac print];
        
    }
   
    return 0;
}

Fraction.h

#import <Foundation/Foundation.h>

@interface Fraction : NSObject {
    //NSInteger *numerator;
    //NSInteger *denominator;
    NSString *userName;
}


-(void) print;
/*
-(void) setNumerator: (int) d;
-(void) setDenominator: (int) d;
-(int) numerator;
-(int) denominator;
*/

//@property (nonatomic, copy) NSInteger *numerator;
@property (nonatomic, copy) NSString *userName;

@end

 

Fraction.m

#import "Fraction.h"
#import <stdio.h>

@implementation Fraction

/*
-(void) print {
    printf( "%i/%i", numerator, denominator );
}
-(void) setNumerator: (int) n {
    numerator = n;
}
-(void) setDenominator: (int) d {
    denominator = d;
}
-(int) denominator {
    return denominator;
}
-(int) numerator {
    return numerator;
}
*/
@synthesize userName = _userName;

-(void) print {
    NSString *nameString = self.userName;
    if (nameString.length == 0) {
        nameString = @"World";
    }
    NSString *greeting = [[NSString alloc] initWithFormat:@"Hello, %@!", nameString];
    //NSLog(@"Hello, %@",nameString);
    printf("%s\n" , [greeting UTF8String]);
}

@end