Question

我需要访问NSArray并从中获取一个值：

-(IBAction) randClicked:(id)sender
{
int randNum;

//when user clicks the button
//create random number, 1 - 32
randNum = arc4random() %32;

如你所见，我可以在这里显示我的随机数：

///using this code for testing random number when button is clicked
NSString *randValText = [[NSString alloc]initWithFormat:@"%d", randNum];
//Output random number to label  
labelRandText.text = randValText;

//Call method seeImage with SEL methodSelector
SEL methodSelector = @selector(seeImage);

///set image opacity to 0
wisdomView.alpha = 0.0; 
//Use NSTimer to call method
[NSTimer scheduledTimerWithTimeInterval:0 target:self selector:methodSelector userInfo:nil repeats:NO];

[randValText release];
}

但是现在，我需要比较randNum的值并访问图像的NSArray，因为它在数组中的位置，所以我可以在UIImageView中显示图像。

很难想出这个问题。非常感谢所有帮助。谢谢你的时间。

这是我在Josh的帮助下实施的当前代码，截至2010年7月6日晚11点13分。我想我几乎拥有它......但我正在做的事情不起作用。我一直收到警告“方法”-objectAtIndex not found（返回类型默认为'id'）

//Call method seeImage with SEL methodSelector
SEL methodSelector = @selector(seeImage);
//Use NSTimer to call method
[NSTimer scheduledTimerWithTimeInterval:0 target:self selector:methodSelector userInfo:[NSNumber numberWithInt:randNum] repeats:NO];

[randValText release];

}

////This is the method to make the graphic choosen by randNum to display at the top of the screen
-(IBAction) seeImage: (NSTimer *)tim
{
CGContextRef imageContext = UIGraphicsGetCurrentContext();
    int randNum = [(NSNumber *)[tim userInfo] intValue];

    UIImage *imgToDisplay = [wisdomView objectAtindex:randNum];
    wisdomView.image = imgToDisplay;

    wisdomView.animationImages = [NSArray arrayWithObjects: 
                                [UIImage imageNamed:@"0.png"],
                                [UIImage imageNamed:@"1.png"],
                                [UIImage imageNamed:@"2.png"],
                                [UIImage imageNamed:@"3.png"],
                                [UIImage imageNamed:@"4.png"],
                                [UIImage imageNamed:@"5.png"],
                                [UIImage imageNamed:@"6.png"],
                                [UIImage imageNamed:@"7.png"],
                                [UIImage imageNamed:@"8.png"],
                                [UIImage imageNamed:@"9.png"],
                                [UIImage imageNamed:@"10.png"],
                                [UIImage imageNamed:@"11.png"],
                                [UIImage imageNamed:@"12.png"],
                                [UIImage imageNamed:@"13.png"],
                                [UIImage imageNamed:@"14.png"],
                                [UIImage imageNamed:@"15.png"],
                                [UIImage imageNamed:@"16.png"],
                                [UIImage imageNamed:@"17.png"],
                                [UIImage imageNamed:@"18.png"],
                                [UIImage imageNamed:@"19.png"],
                                [UIImage imageNamed:@"20.png"],
                                [UIImage imageNamed:@"21.png"],
                                [UIImage imageNamed:@"22.png"],
                                [UIImage imageNamed:@"23.png"],
                                [UIImage imageNamed:@"24.png"],
                                [UIImage imageNamed:@"25.png"],
                                [UIImage imageNamed:@"26.png"],
                                [UIImage imageNamed:@"27.png"],
                                [UIImage imageNamed:@"28.png"],
                                [UIImage imageNamed:@"29.png"],
                                [UIImage imageNamed:@"30.png"],
                                [UIImage imageNamed:@"31.png"],nil]; 

wisdomView.alpha = 0;   
[UIView beginAnimations:nil context:imageContext];
[UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
[UIView setAnimationDuration:4];
[UIView setAnimationDelegate:self];
wisdomView.alpha = 1;
[UIView commitAnimations];

    SEL methodSelector = @selector(hideImage);
    [NSTimer scheduledTimerWithTimeInterval:4 target:self selector:methodSelector userInfo:nil repeats:NO];

}

我很感激帮助。谢谢你的时间。

这是改变后的代码仍然不起作用....我不理解某些东西。 2011年7月7日下午1:19

-(IBAction) seeImage:(NSTimer *)tim
{
NSArray *wisdom;

   wisdom = [[NSArray alloc] initWithObjects: 
                                [UIImage imageNamed:@"0.png"],
                                [UIImage imageNamed:@"1.png"],
                                [UIImage imageNamed:@"2.png"],
                                [UIImage imageNamed:@"3.png"],
                                [UIImage imageNamed:@"4.png"],
                                [UIImage imageNamed:@"5.png"],
                                [UIImage imageNamed:@"6.png"],
                                [UIImage imageNamed:@"7.png"],
                                [UIImage imageNamed:@"8.png"],
                                [UIImage imageNamed:@"9.png"],
                                [UIImage imageNamed:@"10.png"],
                                [UIImage imageNamed:@"11.png"],
                                [UIImage imageNamed:@"12.png"],
                                [UIImage imageNamed:@"13.png"],
                                [UIImage imageNamed:@"14.png"],
                                [UIImage imageNamed:@"15.png"],
                                [UIImage imageNamed:@"16.png"],
                                [UIImage imageNamed:@"17.png"],
                                [UIImage imageNamed:@"18.png"],
                                [UIImage imageNamed:@"19.png"],
                                [UIImage imageNamed:@"20.png"],
                                [UIImage imageNamed:@"21.png"],
                                [UIImage imageNamed:@"22.png"],
                                [UIImage imageNamed:@"23.png"],
                                [UIImage imageNamed:@"24.png"],
                                [UIImage imageNamed:@"25.png"],
                                [UIImage imageNamed:@"26.png"],
                                [UIImage imageNamed:@"27.png"],
                                [UIImage imageNamed:@"28.png"],
                                [UIImage imageNamed:@"29.png"],
                                [UIImage imageNamed:@"30.png"],
                                [UIImage imageNamed:@"31.png"],nil]; 

    int randNum = [(NSNumber *)[tim userInfo] intValue];

    CGContextRef imageContext = UIGraphicsGetCurrentContext();
    UIImage *imgToDisplay = [wisdom objectAtIndex:randNum];
    wisdomView.image = imgToDisplay;

仍然得到方法'-objectAtIndex：'未找到警告，现在''可能无法响应'''NSArray'可能无法响应'-objectAtIndex'。 Arrrrgggg。

感谢您的时间。

Answer 1

将生成的号码塞进计时器的user info位：

[NSTimer scheduledTimerWithTimeInterval:0 
                                 target:self 
                               selector:@selector(seeImage:)
                               userInfo:[NSNumber numberWithInt:randNum]
                                repeats:NO];

然后在计时器的方法中将其恢复。顺便说一句，计时器方法应该有一个参数。*计时器将自己传递给方法就是这样的情况，即，当你需要发送一些信息以便在它发生时使用。

- (void) seeImage: (NSTimer *)tim {
    // Retrieve the NSNumber, using a cast because userInfo returns id
    int randNum = [(NSNumber *)[tim userInfo] intValue];

    NSImage * imgToDisplay = [arrayOfImgs objectAtIndex:randNum];

    // and so on...
}

*虽然它们可以使用任意数量的参数，包括0。

Answer 2

尝试：

[imageArray objectAtIndex:randNum]

编辑：根据评论中的其他信息，我认为@Josh Caswell的回答更能回答这个问题。

Answer 3

//创建随机数，1 - 32 randNum = arc4random（）％32;

会给你0 - 31.检查数组范围。

Answer 4

我修好了！谢谢Josh的帮助！

-(IBAction) seeImage
{          
int randNum;

//when user clicks the button
//create random number, 0 - 31
randNum = arc4random() %32;

NSString *randValText = [[NSString alloc]initWithFormat:@"%d", randNum];
//Output random number to label - testing code 
//labelRandText.text = randValText;

///set image opacity to 0
wisdomView.alpha = 0.0; 

wisdom = [[NSArray alloc] initWithObjects: 
          [UIImage imageNamed:@"0.png"],
          [UIImage imageNamed:@"1.png"],
          [UIImage imageNamed:@"2.png"],
          [UIImage imageNamed:@"3.png"],
          [UIImage imageNamed:@"4.png"],
          [UIImage imageNamed:@"5.png"],
          [UIImage imageNamed:@"6.png"],
          [UIImage imageNamed:@"7.png"],
          [UIImage imageNamed:@"8.png"],
          [UIImage imageNamed:@"9.png"],
          [UIImage imageNamed:@"10.png"],
          [UIImage imageNamed:@"11.png"],
          [UIImage imageNamed:@"12.png"],
          [UIImage imageNamed:@"13.png"],
          [UIImage imageNamed:@"14.png"],
          [UIImage imageNamed:@"15.png"],
          [UIImage imageNamed:@"16.png"],
          [UIImage imageNamed:@"17.png"],
          [UIImage imageNamed:@"18.png"],
          [UIImage imageNamed:@"19.png"],
          [UIImage imageNamed:@"20.png"],
          [UIImage imageNamed:@"21.png"],
          [UIImage imageNamed:@"22.png"],
          [UIImage imageNamed:@"23.png"],
          [UIImage imageNamed:@"24.png"],
          [UIImage imageNamed:@"25.png"],
          [UIImage imageNamed:@"26.png"],
          [UIImage imageNamed:@"27.png"],
          [UIImage imageNamed:@"28.png"],
          [UIImage imageNamed:@"29.png"],
          [UIImage imageNamed:@"30.png"],
          [UIImage imageNamed:@"31.png"],nil]; 

CGContextRef imageContext = UIGraphicsGetCurrentContext();

//pick image randNum index position
wisdomView.image = [wisdom objectAtIndex:randNum];

wisdomView.alpha = 0.0;

[UIView beginAnimations:nil context:imageContext];
[UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
[UIView setAnimationDuration:4];
[UIView setAnimationDelegate:self];
wisdomView.alpha = 1;
[UIView commitAnimations];

SEL methodSelector = @selector(hideImage);
[NSTimer scheduledTimerWithTimeInterval:4 target:self selector:methodSelector userInfo:nil repeats:NO];
[randValText release];

}

感谢您的时间！

无法使用randNum访问NSArray中的对象

4 个答案: