Posts Tagged Objective-C

iPhone tip #2 – What is my current location?

Posted by Samuel in iPhone on April 9, 2009

The iPhone has GPS built-in, which makes the phone really powerful and enables developers to innovate cool and cutting edge applications!

The iPhone devcenter has some sample code explaining how the CoreLocation framework works. But, I found that example a bit hard to understand…

Here is an easier way of finding your current location from your iPhone.

Let’s start with the interface/header file.
CurrentLocationController.h

#import <CoreLocation/CoreLocation.h>
 
@interface CurrentLocationController : NSObject <CLLocationManagerDelegate> {
	CLLocationManager *locationManager;
}
 
@property (nonatomic, retain) CLLocationManager *locationManager;
 
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation;
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error;
 
@end

Note: Our object “implements” the CLLocationManagerDelegate protocol. We “implement” two methods, locationManager:didUpdateToLocation:fromLocation: and locationManager:didFailWithErrorfrom :, from CLLocationManagerDelegate. The first method is invoked when a new location is available and the second one if an error has occurred.

Here comes the implementation:

#import "CurrentLocationController.h"
 
@implementation CurrentLocationController
 
@synthesize locationManager;
 
- (id) init {
    self = [super init];
    if (self != nil) {
        self.locationManager = [[[CLLocationManager alloc] init] autorelease];
        self.locationManager.delegate = self;
    }
    return self;
}
 
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
    NSLog([newLocation description]);
}
 
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
    NSLog([error description]);
}
 
- (void)dealloc {
    [self.locationManager release];
    [super dealloc];
}
 
@end

The only important thing to note is the line

self.locationManager.delegate = self;

. Here we set our own object as the delegate, which means that all the location messages will be forwarded to CurrentLocationController.

I hope this will give you more time innovating, instead of developing Trichotillomania.

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iPhone tip #1 – URL encoding in Objective-C

Posted by Samuel in iPhone on April 8, 2009

If you are n00b when it comes to iPhone development, then you’ve come to the right place! We’ll be posting howtos, tips and tricks continuously.

So, how do you URL enconde a string? It’s quite simple if you know how. :) 

+ (NSString *)urlEncodeValue:(NSString *)str
{
NSString *result = (NSString *) CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)str, NULL, CFSTR(”:/?#[]@!$&’()*+,;=”), kCFStringEncodingUTF8);
return [result autorelease];
}

To create an URL object, do like this:

[NSURL URLWithString:encodedUrlString]

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