- (void)setupDefaults {
    //get the plist location from the settings bundle
    NSString *settingsPath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:@"Settings.bundle"];
    NSString *plistPath = [settingsPath stringByAppendingPathComponent:@"Root.plist"];
 
    //get the preference specifiers array which contains the settings
    NSDictionary *settingsDictionary = [NSDictionary dictionaryWithContentsOfFile:plistPath];
    NSArray *preferencesArray = [settingsDictionary objectForKey:@"PreferenceSpecifiers"];
 
    //use the shared defaults object
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
 
    //for each preference item, set its default if there is no value set
    for(NSDictionary *item in preferencesArray) {
 
        //get the item key, if there is no key then we can skip it
        NSString *key = [item objectForKey:@"Key"];
        if (key) {
 
            //check to see if the value and default value are set
            //if a default value exists and the value is not set, use the default
            id value = [defaults objectForKey:key];
            id defaultValue = [item objectForKey:@"DefaultValue"];
            if(defaultValue && !value) {
                [defaults setObject:defaultValue forKey:key];
            }
        }
    }
 
    //write the changes to disk
    [defaults synchronize];
}

main.m
 
#import <objc/runtime.h>
Method getDistanceFrom = class_getInstanceMethod([CLLocation class], @selector(getDistanceFrom:));
class_addMethod([CLLocation class], @selector(distanceFromLocation:),
method_getImplementation(getDistanceFrom),
method_getTypeEncoding(getDistanceFrom));