在 iOS 中下载 zip 文件

Question

尝试从给定的 URL 下载 zip 文件，因为 zip 文件每天都会更新，我在 ApplicationDidFinishLunching 方法中编写了代码，但它不起作用。我的代码有什么问题吗？

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    NSString *stringURL = @"http://webspace.apiit.edu.my/intake-timetable/download_timetable/timetableXML.zip";
    NSURL  *url = [NSURL URLWithString:stringURL];
    NSData *urlData = [NSData dataWithContentsOfURL:url];
    //Find a cache directory. You could consider using documenets dir instead (depends on the data you are fetching)
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *path = [paths  objectAtIndex:0];

    //Save the data
    NSString *dataPath = [path stringByAppendingPathComponent:@"timetableXML.zip"];
    dataPath = [dataPath stringByStandardizingPath];
    [urlData writeToFile:dataPath atomically:YES];
    return YES;
}

Answer 1

试试这个，因为它会在后台下载 zip 文件。即使文件只有几 kb，下载也可能需要一些时间，并且由于下载是在主线程上执行的，这将阻止应用程序启动！

dispatch_queue_t queue = dispatch_get_global_queue(0,0);
dispatch_async(queue, ^{

    NSLog(@"Beginning download");
    NSString *stringURL = @"http://webspace.apiit.edu.my/intake-timetable/download_timetable/timetableXML.zip";
    NSURL  *url = [NSURL URLWithString:stringURL];
    NSData *urlData = [NSData dataWithContentsOfURL:url];

    //Find a cache directory. You could consider using documenets dir instead (depends on the data you are fetching)
    NSLog(@"Got the data!");
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *path = [paths  objectAtIndex:0];

    //Save the data
    NSLog(@"Saving");
    NSString *dataPath = [path stringByAppendingPathComponent:@"timetableXML.zip"];
    dataPath = [dataPath stringByStandardizingPath];
    [urlData writeToFile:dataPath atomically:YES];

});

你不应该在主线程上下载任何东西，因为它会“阻塞”你的应用程序。但是应该注意的是，还有比这更好的方法来下载数据。例如阅读this。