Question

我有目标C代码：

NSString * url = [NSString stringWithFormat:@"http://tragicclothing.co.uk/Retort/imageupload.php"];
    NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
    [request setHTTPMethod:@"POST"];
    NSString *boundary = @"---------------------------14737809831466499882746641449";
    NSMutableData *body = [[NSMutableData alloc]init];
    [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"image\"; filename=\"image.jpg\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[@"Content-Type: audio/basic\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:_imageDataToSend];
    [body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [request setHTTPBody:body];
    NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];
    [request addValue:contentType forHTTPHeaderField: @"Content-Type"];

    //Send the Request
    NSData* returnData = [NSURLConnection sendSynchronousRequest: request
                                               returningResponse: nil error: nil];
    //serialize to JSON
    NSDictionary *result = [NSJSONSerialization JSONObjectWithData:returnData options:NSJSONReadingMutableContainers error:nil];

    //parsing JSON
    bool success = [result[@"success"] boolValue];
    if(success){ 
        NSLog(@"Success=%@",result[@"msg"]); 
    }else{ 
        NSLog(@"Fail=%@",result[@"msg"]);
    }

当连接到互联网时它工作正常，但是当它不是我得到错误时：

由于未捕获的异常终止应用＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39;数据参数为nil＆＃39;

Answer 1

if (!returnData){
    return; // or handle no connection error here
}else{
   NSDictionary *result = [NSJSONSerialization JSONObjectWithData:returnData options:NSJSONReadingMutableContainers error:nil];

    //parsing JSON
    bool success = [result[@"success"] boolValue];
   if(success){ 
        NSLog(@"Success=%@",result[@"msg"]); 
   }else{ 
       NSLog(@"Fail=%@",result[@"msg"]);
   }
}

Answer 2

在执行网络请求之前，您必须检查连接性。

获得downloaded并导入Reachbility.m和Reachbility.h个文件

后

创建辅助函数：

-(BOOL)IsConnected{
  Reachability *reachability = [Reachability reachabilityForInternetConnection];
  NetworkStatus networkStatus = [reachability currentReachabilityStatus];

  return !(networkStatus == NotReachable);    
}

然后使用它

if([self IsConnected]){
 //connected!
 //upload your image
}
else{
  //not connected to internet!
}

非常重要

如果您的项目未使用arc

转到目标＆gt;
构建阶段＆gt;
双击“可达性文件”
添加-fno-objc-arc

Answer 3

应用程序正在崩溃

NSDictionary *result = [NSJSONSerialization JSONObjectWithData:returnData options:NSJSONReadingMutableContainers error:nil];

因为returnData的值为nil。您需要做的就是在传递到NSJSONSerialization之前测试此对象是否为nil

NSData* returnData = [NSURLConnection sendSynchronousRequest: request
                                           returningResponse: nil error: nil];

if (returnData == nil)
{
    // Handle No Data returned from server
    // This can happen from no internet connection, from a server error or many other things
}
else 
{
    // Parse the Data
    NSDictionary *result = [NSJSONSerialization JSONObjectWithData:returnData options:NSJSONReadingMutableContainers error:nil];

    //parsing JSON
    bool success = [result[@"success"] boolValue];
    if(success){ 
        NSLog(@"Success=%@",result[@"msg"]); 
    }else{ 
        NSLog(@"Fail=%@",result[@"msg"]);
    }
}

如何在没有互联网连接时上传图像时防止应用崩溃

3 个答案: