制作stringWithContentsOfURL异步 - 它是安全的吗？

问题描述

我试图使 - [的NSString stringWithContentsOfURL：编码：错误：]异步的，由后台线程运行它，共时：

I attempted to make -[NSString stringWithContentsOfURL:encoding:error:] asynchronous, by running it a-synchronically from a background thread:

__block NSString *result;
dispatch_queue_t currentQueue = dispatch_get_current_queue();

void (^doneBlock)(void) = ^{
    printf("done! %s",[result UTF8String]);
};

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
                                         (unsigned long)NULL), ^(void) {
    result = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://www.google.com/"] encoding:NSUTF8StringEncoding error:nil];
    dispatch_sync(currentQueue, ^{
        doneBlock();
    });
});

它的做工精细，最重要的是，它的异步的。

Its working fine, and most importantly, its asynchronous.

我的问题是，如果它是安全的这样做，否则可能有任何线程问题等？

My question is if it's safe to do this, or could there be any threading problems etc.?

在此先感谢：）

推荐答案

这应该是安全的，但为什么另起炉灶？

That should be safe, but why reinvent the wheel?

NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.google.com"]];
[NSURLConnection sendAsynchronousRequest:req queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
    NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    // etc
}];

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