blocks|key|1675778|text|在这种情况下，initWithData:方法应该返回nil。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1675779|尝试：|1675780|UIImage+*myImage+=+[[UIImage+alloc]+initWithData:imgData];
if(!myImage)+{
++++//+problem
}|code-block|syntax|javascript|1675781|entityMap^0|7|D|Q|3|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

The <code>initWithData:</code> method should return <code>nil</code> in such cases.

Try :

<pre><code>UIImage *myImage = [[UIImage alloc] initWithData:imgData];
if(!myImage) {
 // problem
}
</code></pre>

blocks|key|1675824|text|堆栈溢出上有一个与此类似的线程：Catching+error:+Corrupt+JPEG+data:+premature+end+of+data+segment。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1675825|解决方案是检查报头字节FF+D8和结束字节FF+D9。所以，如果你在NSData中有图像数据，你可以像这样检查它：|style|CODE|1675826|-+(BOOL)isJPEGValid:(NSData+*)jpeg+{
++++if+([jpeg+length]+<+4)+return+NO;
++++const+char+*+bytes+=+(const+char+*)[jpeg+bytes];
++++if+(bytes[0]+!=+0xFF+%7C%7C+bytes[1]+!=+0xD8)+return+NO;
++++if+(bytes[[jpeg+length]+-+2]+!=+0xFF+%7C%7C+bytes[[jpeg+length]+-+1]+!=+0xD9)+return+NO;
++++return+YES;
}|code-block|syntax|javascript|1675827|然后，要检查JPEG数据是否无效，只需编写：|1675828|if+(![self+isJPEGValid:myData])+{
++++NSLog(@"Do+something+here");
}|1675829|希望这能有所帮助！|1675830|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/3848280/catching-error-corrupt-jpeg-data-premature-end-of-data-segment^0|G|1S|0|0|B|5|L|5|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]]|C|$]]|$1|D|3|E|5|6|7|14|8|@$A|15|B|16|F|G]|$A|17|B|18|F|G]]|9|@]|C|$]]|$1|H|3|I|5|J|7|19|8|@]|9|@]|C|$K|L]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|C|$]]|$1|O|3|P|5|J|7|1B|8|@]|9|@]|C|$K|L]]|$1|Q|3|R|5|6|7|1C|8|@]|9|@]|C|$]]|$1|S|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|Z]]]]

There is a similar thread to this one on stack overflow: <a href="https://stackoverflow.com/questions/3848280/catching-error-corrupt-jpeg-data-premature-end-of-data-segment">Catching error: Corrupt JPEG data: premature end of data segment</a>.

There solution is to check for the header bytes <code>FF D8</code> and ending bytes <code>FF D9</code>. So, if you have image data in an NSData, you can check it like so:

<pre><code>- (BOOL)isJPEGValid:(NSData *)jpeg {
 if ([jpeg length] &lt; 4) return NO;
 const char * bytes = (const char *)[jpeg bytes];
 if (bytes[0] != 0xFF || bytes[1] != 0xD8) return NO;
 if (bytes[[jpeg length] - 2] != 0xFF || bytes[[jpeg length] - 1] != 0xD9) return NO;
 return YES;
}
</code></pre>

Then, to check if JPEG data is invalid, just write:

<pre><code>if (![self isJPEGValid:myData]) {
 NSLog(@"Do something here");
}
</code></pre>

Hope this helps!

blocks|key|70523|text|在这种情况下，我也遇到过同样的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|70524|结果是，我将一个NSMutableData实例传递给全局队列进行解码。在解码过程中，NSMutableData中的数据被从网络接收到的下一帧所覆盖。|70525|我已经通过传递数据的副本修复了错误。使用缓冲池来提高性能可能会更好：|70526|++++NSData+*dataCopy+=+[_receivedData+copy];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,+0),+%5E{
++++ZAssert([self+isJPEGValid:dataCopy],+@"JPEG+data+is+invalid");+//+should+never+happen
++++UIImage+*image+=+[UIImage+imageWithData:dataCopy];
++++dispatch_async(dispatch_get_main_queue(),+%5E{
++++++++//+show+image
++++});
});|code-block|syntax|javascript|70527|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I've encountered the same problem in this exact situation.

It turned out that I was passing an instance of NSMutableData to global queue for decoding. During decoding the data in NSMutableData was overwritten by next frame received from network.

I've fixed the errors by passing a copy of the data. It might be better to use a buffer pool to improve performance:

<pre><code> NSData *dataCopy = [_receivedData copy];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
 ZAssert([self isJPEGValid:dataCopy], @"JPEG data is invalid"); // should never happen
 UIImage *image = [UIImage imageWithData:dataCopy];
 dispatch_async(dispatch_get_main_queue(), ^{
 // show image
 });
});
</code></pre>

i have an MJPEG stream over RTSP/UDP from which i want to generate JPEGs for a UIImageView with [UIImage initWithData:]. Most of the time this works good, but sometimes i get corrupt images and log messages like:

<pre><code>ImageIO: &lt;ERROR&gt; JPEGCorrupt JPEG data: premature end of data segment
</code></pre>

My Question is: how can i see (during runtime), that such message occurs? Unfortunatly 'initWithData' has no error output, is there any other way?

Thank you.

Edit: in this case, the initWithData does return a valid UIImage object, not nil!

How to get errors/warnings in [UIImage initWithData:]

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个基于RTSP/UDP的MJPEG流，我想从这个流中用UIImage initWithData:为UIImageView生成MJPEG。大多数情况下，这样做效果很好，但有时我会得到损坏的图像和日志消息，如：ImageIO: <ERROR> JPEGCorrupt JPEG data: premature end ...

问如何在[UIImage initWithData:]中获取错误/警告
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问如何在[UIImage initWithData:]中获取错误/警告EN