AFNetWorking Crash: Invalid parameter not satisfying: URLString

AFNetWorking出现的崩溃报错：

[Bugly]  Trapped uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying: URLString' 

原因：是AFNetWorking内部有一个这个方法：

NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];

如果URLString含有非法字符时，比如前后有空格。这个方法[NSURL URLWithString:URLString relativeToURL:self.baseURL]会返回nil，从而在方法内部的NSParameterAssert(URLString);处抛出异常，导致崩溃：

(lldb) po [[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString]
 nil
(lldb) po [NSURL URLWithString:URLString relativeToURL:self.baseURL]
 nil
(lldb) po [NSURL URLWithString:URLString]
 nil
(lldb) po URLString
 http://10.161.0.169:8092/Spring/PayV647/do 

解决方案：传入URLString之前，先将其编码：

URLString = [URLString stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];