*** Assertion failure in -[AFJSONRequestSerializer requestWithMethod:URLString:parameters:error:],

在使用AFNetworking时，如果Url中包含空格，文字，或者特殊字符时，会崩溃：

[AFJSONRequestSerializer requestWithMethod:URLString:parameters:error:]

解决办法：

NSString *url = [NSString stringWithFormat:@"请求的链接"];

NSString *requestUrl = [url stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];