프로그래밍 방식으로 UIPageControl을 UIScrollView에 연결

프로그래밍 방식으로 UIPageControl을 UIScrollView에 연결

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내 앱에서 간단한 슬라이드 쇼보기를 만들고 있습니다. 내 UIPageControl을 내 UIScrollView에 연결하고 싶습니다. 이것은 너무 어렵지는 않지만 어디에서도 간단한 해결책을 찾을 수 없었습니다. 아래는 내 코드입니다.

HelpViewController.h

#import <UIKit/UIKit.h>

@interface HelpViewController : UIViewController{
}
@end

HelpViewController.m

#import "HelpViewController.h"

@interface HelpViewController ()

@end

@implementation HelpViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    CGRect scrollViewFrame = CGRectMake(0, 62, 320, 404);
    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:scrollViewFrame];
    [self.view addSubview:scrollView];
    CGSize scrollViewContentSize = CGSizeMake(640, 404);
    [scrollView setContentSize:scrollViewContentSize];
    UILabel *label  = [[UILabel alloc] initWithFrame:CGRectMake(200, 200, 50, 21)];
    [label setText:@"Hello"];
    [scrollView addSubview:label];
    [scrollView setPagingEnabled:YES];
    scrollView.showsHorizontalScrollIndicator = NO;
    UIPageControl *pageControl = [[UIPageControl alloc] init]; 
    pageControl.frame = CGRectMake(110,5,100,100); 
    pageControl.numberOfPages = 2; 
    pageControl.currentPage = 0; 
    [self.view addSubview:pageControl];
    pageControl.backgroundColor = [UIColor redColor];
}

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

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

@end

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아마도 이것은 당신을 위해 작동합니다

UIScrollView의 delegate = self (또는 아래 선택기가있는 곳)를 설정하는 것을 잊지 마십시오.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat pageWidth = self.scrollView.frame.size.width; // you need to have a **iVar** with getter for scrollView
    float fractionalPage = self.scrollView.contentOffset.x / pageWidth;
    NSInteger page = lround(fractionalPage);
    self.pageControl.currentPage = page; // you need to have a **iVar** with getter for pageControl
}

코드의 경우 다음과 같습니다.

.h 파일

#import <UIKit/UIKit.h>

@interface HelpViewController : UIViewController{
}

@property (nonatomic, retain) UIScrollView *scrollView;
@property (nonatomic, retain) UIPageControl * pageControl;
@end

.m 파일

#import "HelpViewController.h"

@interface HelpViewController ()

@end

@implementation HelpViewController
@synthesize scrollView=scrollView_;
@synthesize pageControl=pageControl_;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    CGRect scrollViewFrame = CGRectMake(0, 62, 320, 404);
    self.scrollView = [[[UIScrollView alloc] initWithFrame:scrollViewFrame] autorelease];
    self.scrollView.delegate = self;
    [self.view addSubview:self.scrollView];
    CGSize scrollViewContentSize = CGSizeMake(640, 404);
    [self.scrollView setContentSize:scrollViewContentSize];
    UILabel *label  = [[UILabel alloc] initWithFrame:CGRectMake(200, 200, 50, 21)];
    [label setText:@"Hello"];
    [self.scrollView addSubview:label];
    [self.scrollView setPagingEnabled:YES];
    self.scrollView.showsHorizontalScrollIndicator = NO;
    self.pageControl = [[[UIPageControl alloc] init] autorelease]; 
    self.pageControl.frame = CGRectMake(110,5,100,100); 
    self.pageControl.numberOfPages = 2; 
    self.pageControl.currentPage = 0; 
    [self.view addSubview:self.pageControl];
    pageControl.backgroundColor = [UIColor redColor];
}

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

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

 - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
        CGFloat pageWidth = self.scrollView.frame.size.width;
        float fractionalPage = self.scrollView.contentOffset.x / pageWidth;
        NSInteger page = lround(fractionalPage);
        self.pageControl.currentPage = page; 
    }


@end

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이것은 실제로 설정이 매우 간단합니다. 먼저 스크롤보기와 페이지 컨트롤을 만들어야합니다. UIScrollViewDelegate클래스의 인터페이스에서 구현해야합니다 .

    UIScrollView * scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * 3, scrollView.frame.size.height);
    scrollView.delegate = self;

    UIPageControl * pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(0, 90, scrollView.frame.size.width, 20)];
    pageControl.numberOfPages = scrollView.contentSize.width/scrollView.frame.size.width;
    [pageControl addTarget:self action:@selector(changePage:) forControlEvents:UIControlEventValueChanged];

그런 다음 다음 두 가지 방법을 추가해야합니다.

- (IBAction)changePage:(id)sender {
    CGFloat x = pageControl.currentPage * scrollView.frame.size.width;
    [scrollView setContentOffset:CGPointMake(x, 0) animated:YES];
}

-(void) scrollViewDidEndDecelerating:(UIScrollView *)scrollView  {
    NSInteger pageNumber = roundf(scrollView.contentOffset.x / (scrollView.frame.size.width));
    pageControl.currentPage = pageNumber;
}

이러한 메서드는 페이지 컨트롤과 스크롤보기간에 필요한 통신을 추가합니다.

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다음 코드는 Swift에서 작동합니다.

func addScrollView() {        
    let scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
    let numberOfPages: CGFloat = 4
    scrollView.contentSize = CGSize(width: scrollView.frame.width * numberOfPages, height: scrollView.frame.height * numberOfPages)
    scrollView.delegate = self
    scrollView.isPagingEnabled = true

    let pageControl = UIPageControl(frame: CGRect(x: 0, y: scrollView.frame.height - 37, width: scrollView.frame.width, height: 37))
    pageControl.numberOfPages = Int(numberOfPages)
    pageControl.currentPage = 0
}

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let value = scrollView.contentOffset.x / scrollView.frame.size.width
    pageControl.currentPage = Int(round(value))
}

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to get exact page index without rounding off the value simply put the pagecontrol.currentpage in the scrollViewDidEndDecelerating delegate method of scroll view.This works for me!

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All these answers are great but I'd like to offer an alternative solution, using ReactiveCocoa!

The following code makes an assumption that you have a property called scrollView and one called pageControl.

[RACObserve(self.scrollView, contentOffset)
  subscribeNext:^(NSValue* value){
      CGPoint offset = [value CGPointValue];
      CGFloat fractional = offset.x/self.scrollView.width;
      [self.pageControl setCurrentPage:lroundf(fractional)];
  }];

All that's going on here is you're observing change on the contentOffset property of the scrollView and calculating the page index on every next event (i.e. every time the property value changes).

The only downside of this is that you have to unbox the CGPoint but on the upside there's no UIScrollViewDelegate code needed at all!

ReferenceURL : https://stackoverflow.com/questions/10198732/programmatically-linking-uipagecontrol-to-uiscrollview