使用按钮在另一个类iOS中调用方法

时间:2012-05-03 20:30:48

标签: ios xcode4 uibutton core-location

我已经看过大多数关于此事的所有其他帖子,但我似乎无法得到它。我是iOS和Objective-C的新手,我正在关注Objective-C和iOS的Big Nerd Ranch指南。我在他们的网站上发现的挑战之一是制作一个简单的CoreLocation应用程序,我试图将代码分离成类,以便我可以在以后再重复使用它,如果我愿意的话。

我想获取ViewController.m文件中的按钮,在MyLocation.m文件中调用locationManager,这是MyLocation类。我已经研究过NSNotificaiton,但我无法正常工作。

我不能为我的生活弄清楚我错过了什么或做错了什么。我为问题的简单性道歉,我正在努力学习尽可能多的基础知识。

以下是我的文件:

ViewController.h:

#import <UIKit/UIKit.h>
#import "MyLocation.h"

@interface ViewController : UIViewController
- (IBAction)GetLocation:(id)sender;
@property (weak, nonatomic) IBOutlet UILabel *LocationOutput;

@end

ViewController.m:

#import "ViewController.h"
#import "MyLocation.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize LocationOutput;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidUnload
{
    [self setLocationOutput:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (IBAction)GetLocation:(id)sender {

    //WHAT GOES HERE?
}
@end

MyLocation.h:

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

@class MyLocation;

@protocol MyLocationDelegate <NSObject>;

@end

@interface MyLocation : NSObject <CLLocationManagerDelegate>
@property (nonatomic, strong) CLLocationManager *locationManager;

@end

MyLocation.m:

#import "MyLocation.h"

@implementation MyLocation
@synthesize locationManager = _locationManager;

-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    NSLog(@"Latitude is: %f", newLocation.coordinate.latitude);
}

@end

我知道我还没有向标签输出任何内容,但我正在做一个NSLog。

感谢您的帮助。我真的很感激。

1 个答案:

答案 0 :(得分:2)

为了向对象发送消息,您需要引用它。在您发布的两个班级中,您遇到了同样的问题:您没有对它们的引用,因此您将无法向它们发送消息。

ViewController中,您需要以某种方式获取对MyLocation对象的引用。例如,如果您将代码更改为:

- (IBAction)GetLocation:(id)sender {
    MyLocation *myLocation = [[[MyLocation alloc] init] autorelease];
    [myLocation someMethod];
}

这将在每次调用操作时实例化一个新的MyLocation对象,并向其发送someMethod消息。在你的情况下,这有点复杂。您的MyLocation类需要实例化CLLocationManager个实例。可能你需要一个实例变量,并做这样的事情:

@interface MyLocation {
    CLLocationManager *_locationMananger;
}
@end

@implementation MyLocation

- (id)init {
   self = [super init];
   if (self) {
       _locationManager = [[CLLocationManager alloc] init];
       _locationManager.delegate = self;
   }
   return self;
}

- (void)dealloc {
   [_locationManager release];

   [super dealloc];
}

@end

然后,您在CLLocationManager上创建的MyLocation实例将在位置更改时调用其委托方法。您应该在该方法中执行的操作是将该位置存储在MyLocation的某个实例变量中,以便稍后可以访问它。

最后,我会更改ViewController以仅在初始化或查看加载时创建MyLocation实例一次:

@interface ViewController {
    MyLocation *_myLocation;
}
@end

@implementation ViewController

- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)bundle {
    self = [super initWithNibName:nibName bundle:bundle];
    if (self) {
        _myLocation = [[MyLocation alloc] init];
    }
    return self;
}

- (void)dealloc {
   [_myLocation release];
   [super dealloc];
}

- (IBAction)GetLocation:(id)sender {
   // Grab the location from _myLocation using a property or method defined
}

@end

希望你能得到这个想法,这可以帮助你开始。