Unrecognized selector error processing results from geocodeAddressString - iphone

Question

I'm trying to create multiple placemarks using MKMapItem without using coordinates.
I used location name directly in geocodeAdressString:#"Mumbai"... but I got result for single location.
While I use multiple locations through array, I'm getting this error:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayI length]: unrecognized selector sent to instance 0xab48380'
Why is this problem occurring?
Class mapItemClass=[MKMapItem class];
if(mapItemClass &&[mapItemClass respondsToSelector:#selector(openMapsWithItems:launchOptions:)])
{
NSArray *addr=[[NSArray alloc ]initWithObjects:#"Banglore",#"Mumbai",#"Delhi", nil];
CLGeocoder *geocoder=[[CLGeocoder alloc]init];
[geocoder geocodeAddressString:addr completionHandler:^(NSArray *placemarks, NSError *error) {
CLPlacemark *geocodedPlacemark=[placemarks objectAtIndex:0];
MKPlacemark *placemark=[[MKPlacemark alloc]initWithCoordinate:geocodedPlacemark.location.coordinate addressDictionary:geocodedPlacemark.addressDictionary];
MKMapItem *mapItem=[[MKMapItem alloc]initWithPlacemark:placemark];
[mapItem setName:geocodedPlacemark.name];
[MKMapItem openMapsWithItems:#[mapItem] launchOptions:nil];
}];
}

Answer 1

The error state that -[__NSArrayI length]: unrecognized selector sent to instance 0xab48380'
NSArray dont have a property length. So it is unable to find the selector of length. So check where you are using NSArray and keep break points to find where error is happening. length is the method of NSString and NSData but NSArray dont have length, it has count

Answer 2

I have been able to replicate this using this code
id array = [[NSArray alloc] initWithObjects:#"Hello", #"World", nil];
NSLog(#"%d",[array length]);
output
-[__NSArrayI length]: unrecognized selector sent to instance 0x96bafe0
notice how I have used id instead of NSArray with using id I am able to call length which isn't allowed by NSArray, but this gets round the compiler when using id.
So the best way to find out where this is going wrong is add an exception that will catch all exceptions. Do this by selecting the exceptions tab in the project navigator wind >> select '+' >> 'Add Exception Breakpoint...' >> then just select done. This will set a breakpoint every time your app throws an exception.
EDIT
Thanks to the code you have added I suspect that you are passing an NSArray where there should be an NSString. You create
NSArray *addr=[[NSArray alloc ]initWithObjects:#"Banglore",#"Mumbai",#"Delhi", nil];
then pass it to geocodeAddressString:addr
[geocoder geocodeAddressString:addr completionHandler:^(NSArray *placemarks, NSError *error) {
Just from the name of this parameter I suspect it should be an NSString and not an NSArray try replacing addr to [addr objectAtIndex:0] this will get the string object at index 0 of the addr array.
EDIT 2
Here is the method you are calling notice it only allows an NSString to be passed in for geocodeAddressString.
- (void)geocodeAddressString:(NSString *)addressString completionHandler:(CLGeocodeCompletionHandler)completionHandler;