如何在滾動視圖轉到視圖2時更改文本標籤？

Question

我正在做一個3級水平滾動的選擇級別 - 滾動控制三個視圖「視圖1」「視圖2」和「視圖3」，我需要對用戶造成幻想，我已經放置了3個按鈕在每個視圖和一半的按鈕在每個面的UIview與2個標籤一個寫「lev」其他「el 2」...

當用戶移動到查看2我希望設置標籤到「el 2」，並且一旦滾動已經在第2級上定位，我想讓標籤寫上「el 1」 - 這會產生錯覺，並且速度太快以至於用戶不會注意到。

繼承人的代碼： 此：

[_elone setText:[NSString stringWithFormat:@"Level 2"]]; 

但我不知道放在哪裏， 我應該做一個出口，一個動作一個說法？

@interface PagerViewController() 
@property (assign) BOOL pageControlUsed; 
@property (assign) NSUInteger page; 
@property (assign) BOOL rotating; 
- (void)loadScrollViewWithPage:(int)page; 
@end 

@implementation PagerViewController 

@synthesize scrollViewTwo; 
@synthesize pageControlTwo; 
@synthesize pageControlUsed = _pageControlUsed; 
@synthesize page = _page; 
@synthesize rotating = _rotating; 

- (void)viewDidLoad 
{ 
[super viewDidLoad]; 
// Do any additional setup after loading the view, typically from a nib. 
[self.scrollViewTwo setPagingEnabled:YES]; 
[self.scrollViewTwo setScrollEnabled:YES]; 
[self.scrollViewTwo setShowsHorizontalScrollIndicator:NO]; 
[self.scrollViewTwo setShowsVerticalScrollIndicator:NO]; 
[self.scrollViewTwo setDelegate:self]; 

} 

- (void)viewWillAppear:(BOOL)animated { 
[super viewWillAppear:animated]; 

for (NSUInteger i =0; i < [self.childViewControllers count]; i++) { 
    [self loadScrollViewWithPage:i]; 
} 

self.pageControlTwo.currentPage = 0; 
_page = 0; 
[self.pageControlTwo setNumberOfPages:[self.childViewControllers count]]; 

UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControlTwo.currentPage]; 
if (viewController.view.superview != nil) { 
    [viewController viewWillAppear:animated]; 
} 

self.scrollViewTwo.contentSize = CGSizeMake(scrollViewTwo.frame.size.width * [self.childViewControllers count], scrollViewTwo.frame.size.height); 
} 

- (void)loadScrollViewWithPage:(int)page { 
if (page < 0) 
    return; 
if (page >= [self.childViewControllers count]) 
    return; 

// replace the placeholder if necessary 
UIViewController *controller = [self.childViewControllers objectAtIndex:page]; 
if (controller == nil) { 
    return; 
} 

// add the controller's view to the scroll view 
if (controller.view.superview == nil) { 
    CGRect frame = self.scrollViewTwo.frame; 
    frame.origin.x = frame.size.width * page; 
    frame.origin.y = 0; 
    controller.view.frame = frame; 
    [self.scrollViewTwo addSubview:controller.view]; 
} 

} 
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView { 
_pageControlUsed = NO; 
} 

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView { 
_pageControlUsed = NO; 
} 

- (IBAction) changePage :(id) sender { 

} 

這是如何完成的？

Answer 1

//落實UIScrollView的委託方法

-(void)scrollViewDidScroll:(UIScrollView *)sender 

{ 

CGFloat pageWidth = yourScrollView.frame.size.width; 
int currentPage = floor((yourScrollView.contentOffset.x - pageWidth/2)/pageWidth) + 1; 

if (currentPage != featureVenPageControll.currentPage) 
{ 
    [_elone setText:[NSString stringWithFormat:@"Level 2"]]; 
} 

}