自定义UIScrollView

本文实现的自定义UIScrollView可以上下拉动，下拉显示前一条记录，上拉显示后一条记录，这里并未给出具体的实现代码，本文中的代码只是使用示例，具体的实现请参考附件。

 

DetailViewController.h

 

#import "VerticalSwipeScrollView.h"

@interface DetailViewController : UIViewController <VerticalSwipeScrollViewDelegate, UIScrollViewDelegate> {
  IBOutlet UIView* headerView;
  IBOutlet UIImageView* headerImageView;
  IBOutlet UILabel* headerLabel;

  IBOutlet UIView* footerView;
  IBOutlet UIImageView* footerImageView;
  IBOutlet UILabel* footerLabel;
  
  VerticalSwipeScrollView* verticalSwipeScrollView;
  NSArray* appData;
  NSUInteger startIndex;
  UIWebView* previousPage;
  UIWebView* nextPage;
}

@property (nonatomic, retain) IBOutlet UIView* headerView;
@property (nonatomic, retain) IBOutlet UIImageView* headerImageView;
@property (nonatomic, retain) IBOutlet UILabel* headerLabel;
@property (nonatomic, retain) IBOutlet UIView* footerView;
@property (nonatomic, retain) IBOutlet UIImageView* footerImageView;
@property (nonatomic, retain) IBOutlet UILabel* footerLabel;
@property (nonatomic, retain) VerticalSwipeScrollView* verticalSwipeScrollView;
@property (nonatomic, retain) NSArray* appData;
@property (nonatomic) NSUInteger startIndex;
@property (nonatomic, retain) UIWebView* previousPage;
@property (nonatomic, retain) UIWebView* nextPage;

@end

  

DetailViewController.m

 

#import "DetailViewController.h"

CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};
CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;};

@interface DetailViewController (PrivateMethods)
- (void)hideGradientBackground:(UIView *)theView;
- (UIWebView *)createWebViewForIndex:(NSUInteger)index;
@end

@implementation DetailViewController

@synthesize headerView, headerImageView, headerLabel;
@synthesize footerView, footerImageView, footerLabel;
@synthesize verticalSwipeScrollView, appData, startIndex;
@synthesize previousPage, nextPage;

- (void)viewDidLoad {
    headerImageView.transform = CGAffineTransformMakeRotation(DegreesToRadians(180));
}

- (void)willAppearIn:(UINavigationController *)navigationController {
    self.verticalSwipeScrollView = [[[VerticalSwipeScrollView alloc] initWithFrame:self.view.frame headerView:headerView footerView:footerView startingAt:startIndex delegate:self] autorelease];
    [self.view addSubview:verticalSwipeScrollView];
}

- (void) rotateImageView:(UIImageView *)imageView angle:(CGFloat)angle {
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.2];
    imageView.transform = CGAffineTransformMakeRotation(DegreesToRadians(angle));
    [UIView commitAnimations];
}

# pragma mark VerticalSwipeScrollViewDelegate

- (void) headerLoadedInScrollView:(VerticalSwipeScrollView *)scrollView {
    [self rotateImageView:headerImageView angle:0];
}

- (void) headerUnloadedInScrollView:(VerticalSwipeScrollView *)scrollView {
    [self rotateImageView:headerImageView angle:180];
}

- (void) footerLoadedInScrollView:(VerticalSwipeScrollView *)scrollView {
    [self rotateImageView:footerImageView angle:180];
}

- (void) footerUnloadedInScrollView:(VerticalSwipeScrollView *)scrollView {
    [self rotateImageView:footerImageView angle:0];
}

- (UIView *) viewForScrollView:(VerticalSwipeScrollView *)scrollView atPage:(NSUInteger)page {
    UIWebView* webView = nil;
    
    if (page < scrollView.currentPageIndex)
        webView = [[previousPage retain] autorelease];
    else if (page > scrollView.currentPageIndex)
        webView = [[nextPage retain] autorelease];
    
    if (!webView)
        webView = [self createWebViewForIndex:page];
    
    self.previousPage = page > 0 ? [self createWebViewForIndex:page-1] : nil;
    self.nextPage = (page == (appData.count-1)) ? nil : [self createWebViewForIndex:page+1];
    
    self.navigationItem.title = [[[appData objectAtIndex:page] objectForKey:@"im:name"] objectForKey:@"label"];
    if (page > 0)
        headerLabel.text = [[[appData objectAtIndex:page-1] objectForKey:@"im:name"] objectForKey:@"label"];
    if (page != appData.count-1)
        footerLabel.text = [[[appData objectAtIndex:page+1] objectForKey:@"im:name"] objectForKey:@"label"];
    
    return webView;
}

- (NSUInteger) pageCount {
    return appData.count;
}

- (UIWebView *) createWebViewForIndex:(NSUInteger)index {
    UIWebView* webView = [[[UIWebView alloc] initWithFrame:self.view.frame] autorelease];
    webView.opaque = NO;
    [webView setBackgroundColor:[UIColor clearColor]];
    [self hideGradientBackground:webView];
    
    NSString* htmlFile = [[[NSBundle mainBundle] bundlePath] stringByAppendingString:@"/DetailView.html"];
    NSString* htmlString = [NSString stringWithContentsOfFile:htmlFile encoding:NSUTF8StringEncoding error:nil];
    htmlString = [htmlString stringByReplacingOccurrencesOfString:@"<!-- title -->" withString:[[[appData objectAtIndex:index] objectForKey:@"im:name"] objectForKey:@"label"]];
    htmlString = [htmlString stringByReplacingOccurrencesOfString:@"<!-- icon -->" withString:[[[[appData objectAtIndex:index] objectForKey:@"im:image"] objectAtIndex:0] objectForKey:@"label"]];
    htmlString = [htmlString stringByReplacingOccurrencesOfString:@"<!-- content -->" withString:[[[appData objectAtIndex:index] objectForKey:@"summary"] objectForKey:@"label"]];
    [webView loadHTMLString:htmlString baseURL:nil];
    
    return webView;
}

- (void) hideGradientBackground:(UIView *)theView {
    for (UIView *subview in theView.subviews) {
        if ([subview isKindOfClass:[UIImageView class]])
            subview.hidden = YES;
        
        [self hideGradientBackground:subview];
    }
}

- (void)viewDidUnload {
    self.headerView = nil;
    self.headerImageView = nil;
    self.headerLabel = nil;
    
    self.footerView = nil;
    self.footerImageView = nil;
    self.footerLabel = nil;
}

- (void)dealloc {
    [headerView release];
    [headerImageView release];
    [headerLabel release];
    
    [footerView release];
    [footerImageView release];
    [footerLabel release];
    
    [verticalSwipeScrollView release];
    [appData release];
    [previousPage release];
    [nextPage release];
    
    [super dealloc];
}

@end