iOS8抛出了以前版本在后台捕获和处理的异常。
参见手册来自ios 5 NSXMLParser是线程安全的但不可重入！确保您没有从NSXMLParser委托调用解析。在你的情况下自我。

iOS8 throws an exception that previous versions caught and handled in the background.
see manual As from ios 5 NSXMLParser is thread safe but not reentrant! make sure you aren't calling parse from your NSXMLParser delegate. "Self" in your case.