NSURLConnection delegate didReceiveData trailing characters in data

Question

I've really struggled to figure out why my web service call is riddled with junk data. I have a UITableViewController that calls the web service and also acts as the NSURLConnectionDelegate. Here is the delegate method of interest, note the NSLog statements. ``` - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { NSLog(@"data %@", [[NSString alloc] initWithUTF8String: [data bytes]]); NSLog(@"before %@", [NSString stringWithUTF8String: self.rawData.bytes]); [self.rawData appendData:data]; NSLog(@"after %@", [NSString stringWithUTF8String: self.rawData.bytes]); } ``` Here is the resulting log after a number of attempts: ``` 2009-07-10 09:04:20.339 SundialInvoice[91493:20b] data {"items": [], "request": "/inventory/delivered.json"} 2009-07-10 09:04:20.339 SundialInvoice[91493:20b] before 2009-07-10 09:04:20.340 SundialInvoice[91493:20b] after {"items": [], "request": "/inventory/delivered.json"} SundialInvoice] [PID 2009-07-10 09:04:23.153 SundialInvoice[9149…

Accepted Answer

I think the garbage comes from the logging:

```
[NSString stringWithUTF8String:self.rawData.bytes]
```

Here you are saying that you want an `NSString` from this C-string (= array of bytes terminated by zero). The problem is that the `bytes` method of `NSData` does not return data terminated by a zero, because it’s an ordinary array, not a C-string. Therefore the `NSString` initializer grabs even the bytes after the end of the received `NSData`, until it reaches some zero byte previously stored in memory.

NSURLConnection delegate didReceiveData trailing characters in data

Solution

Problem