尝试在实例方法中NSLog NSNumber ivar

Question

我正在开发一个跟踪不同歌曲的控制台应用程序.我正在努力让歌曲课程首先开始,并试图将已经为歌曲持续时间分配的nsnumber记录到nslog语句中:

//
//  Song.h
//  MusicCollection.15.9   
//
//  Created by Nicholas Iannone on 1/11/10.
   //  Copyright 2010 __MyCompanyName__. All rights reserved.
   //

   #import <Foundation/Foundation.h>


@interface Song : NSObject {

NSString *songTitle;
NSString *songArtist;
NSString *songAlbum;
NSNumber *SongDuration; 
}
@property (nonatomic, retain) NSString *songTitle, *songArtist, *songAlbum;
@property (nonatomic, retain) NSNumber *SongDuration;

-(id) init;


-(void) printSong;



@end


//
//  Song.m
//  MusicCollection.15.9    
//
//  Created by Nicholas Iannone on 1/11/10.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import "Song.h"


@implementation Song

@synthesize  songTitle, songArtist, songAlbum;
@synthesize SongDuration;

-(id) init
{

if (self = [super init]) {

    [SongDuration numberWithInteger];
}

-(void) printSong
{



NSLog(@"===============Song Info==================");
NSLog (@"|                                       |");
NSLog (@"| %-31s |", [songTitle UTF8String]);
NSLog (@"| %-31s |", [songArtist UTF8String]);
NSLog (@"| %-31s |", [songAlbum UTF8String]);                                       
NSLog (@"| %31@   |"  [self songDuration]);
NSLog (@"|                                       |");
NSLog (@"|                                       |");
NSLog (@"=========================================");

}
@end

基本上我不确定如何在调用print方法时将nsnumber合并到nslog语句中,而且我不确定如何处理这些nsobjects ingeneral它们似乎介于我要创建的对象和ac类型之间.任何关于如何处理这些的澄清将不胜感激.

谢谢,

缺口

Answer 1

要在格式字符串中插入对象的描述,请使用%@.

您可以使用标题/艺术家/专辑NSStrings来完成此操作,因此您无需先调用-UTF8String它们.

为了您的歌曲时长,您可以直接登录了的NSNumber或拨打登录一个浮动或整数表示-floatValue或-integerValue与记录的%f和%d.

例子:

NSLog(@"%@", songTitle);
NSLog(@"%@", songDuration);
NSLog(@"%f", [songDuration floatValue]);
NSLog(@"%d", [songDuration integerValue]);