在ios开发中使用 try 和 catch 来捕获错误。

1. 抛出错误的代码
   

    //如果返回的报文是错误信息，则抛出错误
       if([outParams count] <= 0)
       {
           [NSException raise:@"WebService error" format:@"%@", returnJson4SOAP];
       }

2. 在调用中捕获错误代码
   

   //从soap 信息中解析出CusotmerDetail 对象
       @try
       {
           customerDetail = [[[SoapRtnJsonParser alloc] init] parse2CustomerDtail:[returnSoapXML dataUsingEncoding:NSUTF8StringEncoding]];
       }@catch (NSException * e) {
           NSLog(@"Exception: %@", e);
           UIAlertView * alert =
           [[UIAlertView alloc]
            initWithTitle:@"错误"
            message: [[NSString alloc] initWithFormat:@"%@",e]
            delegate:self
            cancelButtonTitle:nil
            otherButtonTitles:@"OK", nil]; 
           [alert show];
           [alert release];
           return;
       }