MBProgressHUD 方便建造thread, 並且不檔到navigation item（比如back）

http://github.com/matej/MBProgressHUD

.h檔部分
#import "MBProgressHUD.h"  
.....{
     
    MBProgressHUD *HUD;
}

.m檔部分
- (void) viewDidLoad{
    
    [super viewDidLoad];

    HUD = [[MBProgressHUD alloc] initWithView:self.tv];
    // 這裡是navigation的item如back在有loading image時可以用的關鍵，記住initWithView不可以指定  self.view，因為這樣以來loading會覆蓋過整個view，關鍵是要另外指定一個較小不是全範圍的view如table view來init.
    [self.tv addSubview:HUD]; 
    // 這裡則是要指定那個較小的view去做addSubview:HUD，如此以來執行的時候也可以按navigation的item了

    HUD.delegate = self;  
    HUD.labelText = @"Loading";  
    [HUD showWhileExecuting:@selector(myTask) onTarget:self withObject:nil animated:YES];
}

- (void) myTask {  
     // Do something usefull in here instead of sleeping ...
     // 背景運作的code如網路載入資料等放這...

}

- (void)hudWasHidden { 

    // Remove HUD from screen when the HUD was hidded  

    [HUD removeFromSuperview];

}

兩個view controller資料傳送呼叫顯示等

---------------------------------------------------------------------------

1 呼叫 2 出來

[self performSegueWithIdentifier:@"upload to location" sender:nil];

---------------------------------------------------------------------------

1 傳送data到 2

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

{

    id dv = segue.destinationViewController;

    [dv setValue:@"123,111" forKey:@"gps"];

}

---------------------------------------------------------------------------

---------------------------------------------------------------------------

2 返回 1 (不透過nav bar 的back button)

    UIViewController *prevVC = [self.navigationController.viewControllers objectAtIndex:1];//1 is level

    [self.navigationController popToViewController:prevVC animated:YES];

指定回去的leval，1就是leavl

---------------------------------------------------------------------------

2 傳送data回 1 (需要實作delegate)

step1 :(在page2的.h檔定義delegate)

//--delegate部分

@protocol page2Delegate <NSObject>

@optional

- (void)passValue:(NSString *)value;

@end

//--

//--

@property (nonatomic, weak) id<LocationDelegate> delegate;

//--

---------------------------------------------------------------------------

step2 : 在page1裡載入delegate

#import "page2.h"//實作協定用

@interface uploadViewController : UIViewController<page2Delegate>

並在page1.m檔裡面實作delegate 方法

- (void)passValue:(NSString *)value{
     //在這裡實作協定
}

---------------------------------------------------------------------------

strp3:在pag1呼叫page2時，指定自己是page2的delegate

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

{

    id dv = segue.destinationViewController;

    [dv setValue:self forKey:@"delegate"];

}

---------------------------------------------------------------------------

step4 :在page2適當的call method，讓delegate執行這個method

[self.delegate passValue:@"pass from 2 data string"];

////類似（  performSegueWithIdentifier ＋ prepareForSegue ）

    /*

    UIStoryboard *storybord = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];

    

    locationViewController *uploadView = [storybord instantiateViewControllerWithIdentifier:@"location"];

    [self.navigationController pushViewController:uploadView animated:YES];

     */