CLGeocoder error EXC_BAD_INSTRUCTION - ios

Question

I'm using CLGeocoder reverseGeocodeLocation. I get the crash after running for about 5-10 minutes (with no noticeable pattern) and get random crashes. Here's my code:
if CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse {
let currentLatCoord = manager.location?.coordinate.latitude
let currentLongCoord = manager.location?.coordinate.longitude
CLGeocoder().reverseGeocodeLocation(CLLocation(latitude: currentLatCoord!, longitude: currentLongCoord!)) { (placemarks, error) -> Void in
if error != nil {
print(error)
return
}
let placeArray = placemarks as [CLPlacemark]!
var placeMark: CLPlacemark
placeMark = placeArray![0]
self.locationLabel.text = String(placeMark.addressDictionary?["Thoroughfare"]!)
}
}
And also, just to help, here's a picture of the line and error:

Answer 1

I think you need some optional binding:
if let thoroughfare = placeMark.addressDictionary?["Thoroughfare"] as? String {
self.locationLabel.text = thoroughfare
}
I'm guessing either there might not be a "Thoroughfare" key in the address dictionary, and you're providing a nil value to the designated initializer for String.
Is there a chance that the view being updated in your code snippet is not on the screen (disposed) when the CLGeocoder has finished its reverse geocoding? If you have your outlet defined as an implicitly unwrapped optional:
#IBOutlet var locationLabel : UILabel!
I'm wondering if it has already been set to nil, but due to the bang (!) the compiler isn't making you check.
But, of course, if your view is still on the screen when you crash, this probably isn't the issue.

Answer 2

You provided us a code sample:
let currentLatCoord = manager.location?.coordinate.latitude
let currentLongCoord = manager.location?.coordinate.longitude
CLGeocoder().reverseGeocodeLocation(CLLocation(latitude: currentLatCoord!, longitude: currentLongCoord!)) { (placemarks, error) -> Void in
if error != nil {
print(error)
return
}
let placeArray = placemarks as [CLPlacemark]!
var placeMark: CLPlacemark
placeMark = placeArray![0]
self.locationLabel.text = String(placeMark.addressDictionary?["Thoroughfare"]!)
}
You can more gracefully handle nil values if you use the if let construct:
CLGeocoder().reverseGeocodeLocation(manager.location!) { placemarks, error in
guard error == nil else {
print(error)
return
}
if let placemark = placemarks?.first {
self.locationLabel.text = placemark.thoroughfare
}
}
And, of course, if you're calling this repeatedly, I wouldn't re-instantiate a new CLGeocoder every time, but hopefully this illustrates the pattern.
But as you can see, you can avoid extracting the latitude and longitude from the location property to only then create a new CLLocation object by simply using manager.location directly. Likewise, you can use the thoroughfare property, which saves you from needing to cast the addressDictionary value.
The key observation, which Craig mentioned above, is to scrupulously avoid using the ! forced unwrapping operator unless you are positive that the variable can never be nil. Likewise, don't use [0] syntax unless you know for a fact that there is at least one item in the array (which is why I use first, which is an optional for which I can easily test).
Frankly, I'd even make sure that the location was valid (not nil and with a non-negative horizontalAccuracy, as a negative value indicates that the coordinates are not valid):
if let location = manager.location where location.horizontalAccuracy >= 0 {
CLGeocoder().reverseGeocodeLocation(location) { placemarks, error in
guard error == nil else {
print(error)
return
}
if let placemark = placemarks?.first {
self.locationLabel.text = placemark.thoroughfare
}
}
}