如何從另一個類調用變量

Question

首先，你們知道有任何優秀的教程網站或書籍來學習如何編寫iOS6代碼嗎？

現在要解決這個問題，我有一個AppDelegate類和一個ViewController類。

我使用AppDelegate類來查找我的當前位置並將其另存爲NSString。

我在我的ViewController類中有一個標籤，我想顯示我的位置。

在java中我通常只是做這樣的事情

label.text = AppDelegate.myLocationString; 

但我是相當新的目標C，我不知道該怎麼做的等價物。說實話，我甚至不確定我是否正在採取這種語言的正確方法。在目標c中是否有另一種方法來處理這個問題？

我試過四處尋找如何做到這一點，但我甚至不確定我是否正確地搜索了我的搜索詞，因此我不知道我是否在正確的方向上搜索。

可能被提供的將是非常讚賞

我的代碼，因爲它現在是任何幫助：

AppDelegate.h

#import <UIKit/UIKit.h> 

#import CoreLocation/CoreLocation.h 

@class BIDViewController; 

@interface BIDAppDelegate : UIResponder <UIApplicationDelegate, CLLocationManagerDelegate> 

@property (strong, nonatomic) UIWindow *window; 

@property (strong, nonatomic) BIDViewController *viewController; 

@property (strong, nonatomic) CLLocationManager *locationManager; 

@property (strong, nonatomic) NSString *myPosition; 

@end 

的LocationManager類從AppDelegate.m

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation 
{ 
    NSDate *eventDate = newLocation.timestamp; 
    NSTimeInterval howRecent = [eventDate timeIntervalSinceNow]; 
    if (abs(howRecent) < 15) { 

     //if it is within the last 15 seconds, use it. Else do nothing. 

     if (newLocation.horizontalAccuracy < 35.0) { 

      //location seems pretty accurate so we will use it 

      NSLog(@"latitude: %+.6f, longitude: %+.6f\n", newLocation.coordinate.latitude, newLocation.coordinate.longitude); 
      NSLog(@"Horizontal accuracy: %f", newLocation.horizontalAccuracy); 

      int latDegrees = newLocation.coordinate.latitude; 
      int lonDegrees = newLocation.coordinate.longitude; 

      double latDecimal = fabs(newLocation.coordinate.latitude - latDegrees); 
      double lonDecimal = fabs(newLocation.coordinate.longitude - lonDegrees); 

      int latMinutes = latDecimal * 60; 
      int lonMinutes = lonDecimal * 60; 

      double latSeconds = ((latDecimal * 3600) - (latMinutes * 60)); 
      double lonSeconds = ((lonDecimal * 3600) - (lonMinutes * 60)); 

      _myPosition = [NSString stringWithFormat:@"Lat: %d, %d, %1.4f, Lon: %d, %d, %1.4f", latDegrees, latMinutes, latSeconds, lonDegrees, lonMinutes, lonSeconds]; 

     } 
    } 
} 

ViewController.h

#import <UIKit/UIKit.h> 

@interface BIDViewController : UIViewController 

@property (weak, nonatomic) IBOutlet UILabel *positionLabel; 

@end 

ViewController.m

#import "BIDViewController.h" 
#import "BIDAppDelegate.h" 

@interface BIDViewController() 

@end 

@implementation BIDViewController 

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

    //I have tried setting the label's text here but to no avail so far, I have been 
    //able to set it as "blah" with the following line: 
    // 
    // positionLabel.text = @"blah"; 
    // 
    //and I have tried things such as the following to populate the label with the 
    //myPosition variable: 
    // 
    // positionLabel.text = _myPosition; 
    //   or 
    // positionLabel.text = AppDelegate._myPosition; 
} 

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

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

@end 

Answer 1

從您的視圖控制器參考應用程序代理，先導入它的定義（你準備好做）：

#import "BIDAppDelegate.h" 

，然後在代碼得到代表：

BIDAppDelegate *appDelegate = (BIDAppDelegate *)[[UIApplication sharedApplication] delegate]; 

，然後從委託獲得位置：

CLLocation *location = appDelegate.locationManager.location; 

，然後打電話給你喜歡的任何方法的位置對象：

NSString *descr = location.description; 

或取得預先計算的位置：

NSString *position = appDelegate.myPosition; 

Answer 2

在你的ViewController

BIDAppDelegate *appDelegate = (BIDAppDelegate *)[UIApplication sharedApplication].delegate; 
[positionLabel setText:appDelegate.myPosition]; 

Answer 3

如何調用從另一個類的變量？

假設你是在ClassB

ClassA *aObj=... ; //create an object of ClassA 
aObj.propertyName=...;//set the property or ivar 
NSString *string=aObj.propertyName;//retrieve it 

---

做你們知道什麼好的教程網站或書籍來學習如何 代碼iOS6的？

http://www.lynda.com/Apple-training-tutorials/106-0.html

http://www.raywenderlich.com/tutorials