Block-based wrapper around Core Location

JWLocationManager.h

#import <Foundation/Foundation.h>
#import <CoreLocation/CoreLocation.h>

typedef void (^JWLocationManagerCallback)(CLLocation *location);
typedef void (^JWLocationManagerErrorCallback)(NSError *error);

@interface JWLocationManager : NSObject <CLLocationManagerDelegate>

@property (nonatomic, copy) NSString *purpose;
@property (nonatomic, copy) JWLocationManagerCallback locationUpdatedBlock;
@property (nonatomic, copy) JWLocationManagerErrorCallback locationErrorBlock;

+ (JWLocationManager *)sharedInstance;
- (void)startUpdatingLocation;
- (void)disableLocationManager;

@end

JWLocationManager.m

#import "JWLocationManager.h"

@interface JWLocationManager()
@property (nonatomic, strong) CLLocationManager *locationManager;
@property (nonatomic, strong) CLLocation *currentLocation;
@end

@implementation JWLocationManager
@synthesize locationManager = _locationManager;
@synthesize locationErrorBlock = _locationErrorBlock;
@synthesize locationUpdatedBlock = _locationUpdatedBlock;


static JWLocationManager *sharedManager = nil;
+ (JWLocationManager *)sharedInstance {
    if (!sharedManager)
        sharedManager = [[self alloc] init];
    
    return sharedManager;
}

- (id)init {
    self = [super init];
    if (!self) return nil;
    
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    self.locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;
    
    return self;
}

- (void)setPurpose:(NSString *)purpose {
    _purpose = [purpose copy];
    self.locationManager.purpose = purpose;
}

- (void)startUpdatingLocation {
    [self.locationManager startUpdatingLocation];
}

- (void)disableLocationManager {
    [self.locationManager stopUpdatingLocation];
    self.locationManager = nil;
    self.currentLocation = nil;
    self.locationErrorBlock = nil;
    self.locationUpdatedBlock = nil;
    
    sharedManager = nil;
}

- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation {
    NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];
    
    if (locationAge > 5.0) return;
    
    if (newLocation.horizontalAccuracy < 0) return;
    
    self.currentLocation = newLocation;
    
    if (self.locationUpdatedBlock)
        self.locationUpdatedBlock(newLocation);
    
    [self.locationManager stopUpdatingLocation];
}

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
    [self.locationManager stopUpdatingLocation];
    
    if (self.locationErrorBlock)
        self.locationErrorBlock(error);
}

@end