在 Obj-C 中随机填充队列

发布于 2024-11-25 20:17:52 字数 577 浏览 1 评论 0原文

现在我正在设置一个基于图像名称的队列，该队列运行良好。它循环遍历图像 0 到 13 并将它们添加到队列中。

loadImagesOperationQueue = [[NSOperationQueue alloc] init];

NSString *imageName;
for (int i=0; i < 13; i++) {
    imageName = [[NSString alloc] initWithFormat:@"cover_%d.jpg", i];
    [(AFOpenFlowView *)self.view setImage:[UIImage imageNamed:imageName] forIndex:i];
    NSLog(@"%d is the index",i);

}

这工作完美；队列设置为从 cover_0.jpg 到 cover_13.jpg。不过，我想为其添加一点随机性。如果我只使用 arc4random() ，毫无疑问我会多次将相同的图像添加到队列中。从逻辑上讲，我怎样才能使 arc4random() 具有独占性。将所选数字添加到字符串中，然后根据当前输出检查它们，如果需要重复 arc4，这是多余且低效的。

原文

Right now I am setting up a queue based off of image names that works fine. It loops through images 0 through 13 and adds them to the queue.

loadImagesOperationQueue = [[NSOperationQueue alloc] init];

NSString *imageName;
for (int i=0; i < 13; i++) {
    imageName = [[NSString alloc] initWithFormat:@"cover_%d.jpg", i];
    [(AFOpenFlowView *)self.view setImage:[UIImage imageNamed:imageName] forIndex:i];
    NSLog(@"%d is the index",i);

}

This works flawlessly; the queue is set up from cover_0.jpg through cover_13.jpg. I want to add a little randomness to it, however. If I just use an arc4random() I will undoubtedly get the same image added to the queue multiple times. Logically, how can I get arc4random() to be exclusive. Adding the chosen numbers to a string and then checking them against the current output, and if needed repeating the arc4, is redundant and inefficient.

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猫卆 2024-12-02 20:17:52

做这样的事情。

NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithCapacity:14];

for (int i = 0; i < 13; i++) {
    [tmpArray addObject:[NSString stringWithFormat:@"cover_%d.jpg", i]];
}

for (int i = 0; i < 13; i++) {
    int index = arc4random() % [tmpArray count];
    NSString *imageName = [tmpArray objectAtIndex:index];
    [tmpArray removeObjectAtIndex:index];
    [(AFOpenFlowView *)self.view setImage:[UIImage imageNamed:imageName] forIndex:i];
}

[tmpArray release];

而且你的代码不应该完美地工作。您正在泄漏imageName。

Do something like this.

NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithCapacity:14];

for (int i = 0; i < 13; i++) {
    [tmpArray addObject:[NSString stringWithFormat:@"cover_%d.jpg", i]];
}

for (int i = 0; i < 13; i++) {
    int index = arc4random() % [tmpArray count];
    NSString *imageName = [tmpArray objectAtIndex:index];
    [tmpArray removeObjectAtIndex:index];
    [(AFOpenFlowView *)self.view setImage:[UIImage imageNamed:imageName] forIndex:i];
}

[tmpArray release];

And your code should not work flawlessly. You are leaking imageName.

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可爱咩 2024-12-02 20:17:52

我会首先用图像名称填充一个数组，然后随机挑选值：

NSMutableArray * imageNames = [NSMutableArray array];
for (int i = 0; i < 13; i++) {
    NSString * iName = [NSString stringWithFormat:@"cover_%d.jpg", i];
    [imageNames addObject:iName];
}
while ([imageNames count] > 0) {
    int index = arc4random() % [imageNames count];
    NSString * iName = [imageNames objectAtIndex:index];
    [imageNames removeObjectAtIndex:index];
    // load image named iName here.
}

I would do it by first populating an array with the image names, and then randomly picking out values:

NSMutableArray * imageNames = [NSMutableArray array];
for (int i = 0; i < 13; i++) {
    NSString * iName = [NSString stringWithFormat:@"cover_%d.jpg", i];
    [imageNames addObject:iName];
}
while ([imageNames count] > 0) {
    int index = arc4random() % [imageNames count];
    NSString * iName = [imageNames objectAtIndex:index];
    [imageNames removeObjectAtIndex:index];
    // load image named iName here.
}

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