启用页面和设备旋转/方向更改的UIScrollView（疯狂）

Question

我很难搞定这个问题。

我有一个启用分页的UIScrollView。它由一个视图控制器（MainViewController）管理，每个页面由PageViewController管理，其视图作为scrollView的子视图添加到正确的偏移量处。滚动是左 - 右的标准方向iPhone应用程序。效果很好。基本上就像苹果提供的示例以及提供给iPhone的天气应用程序一样。

但是，当我尝试支持其他方向时，事情并不顺利。我已经在MainViewController和PageViewController中支持了每个方向，使用了这种方法:

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

然而，当我旋转设备时，我的页面变得相当倾斜，并且出现了许多绘图故障，特别是如果只加载了一些页面，然后我旋转，然后滚动更多等情况...非常混乱。

我已经告诉支持自动调整大小的视图了。

 theView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

但是无济于事。似乎只会拉伸和扭曲我的视图。

在我的 MainViewController 中，我添加了这行代码，试图调整所有页面的视图大小：

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation {
self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * ([self.viewControllers count]), self.scrollView.frame.size.height);

    for (int i = 0; i < [self.viewControllers count]; i++) {
        PageViewController *controller = [self.viewControllers objectAtIndex:i];
        if ((NSNull *)controller == [NSNull null])
            continue;

        NSLog(@"Changing frame: %d", i);
        CGRect frame = self.scrollView.frame;
        frame.origin.x = frame.size.width * i;
        frame.origin.y = 0;
        controller.view.frame = frame;
    }
}

但这并没有帮太多的忙（因为我懒惰地加载了视图，所以当执行此操作时，并非所有视图都必定被加载）。

有没有什么方法可以解决这个问题？

- jbrennan

Answer 1

我已成功使用以下方法实现了这个：

.h文件的代码：

@interface ScrollViewController2 : UIViewController <UIWebViewDelegate, UIScrollViewDelegate> {
NSMutableArray *views;
int currentPage;

IBOutlet UIScrollView *scrollView;
BOOL bolPageControlUsed;
int intCurrIndex;

NSMutableArray *arrayContentData;
NSMutableArray *viewControllers;
}

@property (nonatomic, retain) IBOutlet UIScrollView *scrollView;

@property (nonatomic, retain) NSMutableArray *arrayContentData;
@property (nonatomic, retain) NSMutableArray *viewControllers;
@property (nonatomic) BOOL bolPageControlUsed;
@property (nonatomic) int intCurrIndex;

-(void)bindPages;

- (void)setUpScrollView;
- (void)alignSubviews;

- (NSURLRequest *)getPageFromDocumentsDirectory:(NSString *)pstrPageName;

-(void)initiateScrollView;
-(void)loadScrollViewWithPage:(int)page;

============================================================================================

.m文件

@synthesize scrollView;

@synthesize arrayContentData, viewControllers, bolPageControlUsed, intCurrIndex;

- (void)viewDidLoad {
[super viewDidLoad];

[self bindPages];

//[self setUpScrollView];

[self initiateScrollView];
}

#pragma mark -
#pragma mark Bind Pages
-(void)bindPages{
self.arrayContentData = [[NSMutableArray alloc] init];

[self.arrayContentData addObject:@"1.html"];
[self.arrayContentData addObject:@"2.html"];
[self.arrayContentData addObject:@"3.html"];
[self.arrayContentData addObject:@"4.html"];
[self.arrayContentData addObject:@"5.html"];
[self.arrayContentData addObject:@"6.html"];

[self.arrayContentData addObject:@"1.html"];
[self.arrayContentData addObject:@"2.html"];
[self.arrayContentData addObject:@"3.html"];
[self.arrayContentData addObject:@"4.html"];
[self.arrayContentData addObject:@"5.html"];
[self.arrayContentData addObject:@"6.html"];

[self.arrayContentData addObject:@"1.html"];
[self.arrayContentData addObject:@"2.html"];
[self.arrayContentData addObject:@"3.html"];
[self.arrayContentData addObject:@"4.html"];
[self.arrayContentData addObject:@"5.html"];
[self.arrayContentData addObject:@"6.html"];

[self.arrayContentData addObject:@"1.html"];
[self.arrayContentData addObject:@"2.html"];
[self.arrayContentData addObject:@"3.html"];
[self.arrayContentData addObject:@"4.html"];
[self.arrayContentData addObject:@"5.html"];
[self.arrayContentData addObject:@"6.html"];
}

#pragma mark - 
#pragma mark Get Filename from Document Directory
- (NSURLRequest *)getPageFromDocumentsDirectory:(NSString *)pstrPageName {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDirectory = [paths objectAtIndex:0];
NSString *yourFilePath = [NSString stringWithFormat:@"%@/Html/%@", documentDirectory, pstrPageName];
NSURL *url = [NSURL fileURLWithPath:yourFilePath];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
return requestObj;
}


#pragma mark -
#pragma mark ScrollView Methods
-(void)initiateScrollView{
views = [[NSMutableArray alloc] initWithCapacity:[self.arrayContentData count]];

NSMutableArray *controllers = [[NSMutableArray alloc] init];
for (unsigned i = 0; i < [self.arrayContentData count]; i++) {
    [controllers addObject:[NSNull null]];
}
self.viewControllers = controllers;
[controllers release];

scrollView.contentSize = CGSizeMake([self.arrayContentData count]*scrollView.bounds.size.width,
                                    scrollView.bounds.size.height);
scrollView.delegate = self;

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

// replace the placeholder if necessary
NSString *strContentName = [self.arrayContentData objectAtIndex:page];

//UIImageView *controller = [viewControllers objectAtIndex:page];
UIWebView *controller = [viewControllers objectAtIndex:page];

if ((NSNull *)controller == [NSNull null]) {

    UIView *v = [[UIView alloc] initWithFrame:scrollView.bounds];
    v.backgroundColor = [UIColor colorWithHue:arc4random()/(float)0x100000000
                                   saturation:0.75
                                   brightness:1.0
                                        alpha:1.0];

    controller = [[UIWebView alloc] initWithFrame:v.bounds];
    controller.delegate = self;
    controller.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    controller.center = CGPointMake(v.bounds.size.width/2, v.bounds.size.height/2);
    [controller loadRequest:[self getPageFromDocumentsDirectory:strContentName]];
    [v addSubview:controller];
    [controller release];

    [scrollView addSubview:v];

    [views addObject:v];
    [viewControllers replaceObjectAtIndex:page withObject:controller];
    [v release];
}

[self alignSubviews];

/*
// add the controller's view to the scroll view
if (nil == controller.superview) {
    CGRect frame = scrollView.frame;
    frame.origin.x = frame.size.width * page;
    //frame.origin.y = 0;
    controller.frame = frame;
    [scrollView addSubview:controller];
}*/
}
-(void)scrollViewDidScroll:(UIScrollView *)sender{
// We don't want a "feedback loop" between the UIPageControl and the scroll delegate in
// which a scroll event generated from the user hitting the page control triggers updates from
// the delegate method. We use a boolean to disable the delegate logic when the page control is used.
if (self.bolPageControlUsed) {
    // do nothing - the scroll was initiated from the page control, not the user dragging
    return;
}
// Switch the indicator when more than 50% of the previous/next page is visible

currentPage = scrollView.contentOffset.x / scrollView.bounds.size.width;
[self loadScrollViewWithPage:currentPage];
}

// 在滚动动画结束时，重置布尔值，当滚动源自UIPageControl时使用 - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView { self.bolPageControlUsed = NO; }

#pragma mark -
#pragma mark setUp ScrollView
- (void)setUpScrollView {
// Set up some colorful content views
views = [[NSMutableArray alloc] initWithCapacity:[self.arrayContentData count]];

for (int i = 0; i < [self.arrayContentData count]; i++) {
    UIView *v = [[UIView alloc] initWithFrame:scrollView.bounds];
    v.backgroundColor = [UIColor colorWithHue:arc4random()/(float)0x100000000
                                   saturation:0.75
                                   brightness:1.0
                                        alpha:1.0];

    NSString *strContentName = [self.arrayContentData objectAtIndex:i];

    UIWebView *controller = [[UIWebView alloc] initWithFrame:v.bounds];
    controller.delegate = self;
    controller.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    controller.center = CGPointMake(v.bounds.size.width/2, v.bounds.size.height/2);
    [controller loadRequest:[self getPageFromDocumentsDirectory:strContentName]];
    [v addSubview:controller];
    [controller release];

    [scrollView addSubview:v];

    [views addObject:v];
    [v release];
}

[self alignSubviews];

[scrollView flashScrollIndicators];
}

#pragma mark -
#pragma mark Align Scroll Subviews
- (void)alignSubviews {
// Position all the content views at their respective page positions
scrollView.contentSize = CGSizeMake([self.arrayContentData count]*scrollView.bounds.size.width,
                                    scrollView.bounds.size.height);

NSUInteger i = 0;
for (UIView *v in views) {
    v.frame = CGRectMake(i * scrollView.bounds.size.width, 0,
                         scrollView.bounds.size.width, scrollView.bounds.size.height);

    for (UIWebView *w in v.subviews) {
        [w setFrame:v.bounds];
    }

    i++;
}
}

#pragma mark -
#pragma mark UIWebView delegate
- (void)webViewDidStartLoad:(UIWebView *)webView {
}
- (void)webViewDidFinishLoad:(UIWebView *)webView { 
}


#pragma mark -
#pragma mark Orientation
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations
return YES;
}
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
                            duration:(NSTimeInterval)duration {
currentPage = scrollView.contentOffset.x / scrollView.bounds.size.width;
}
- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
                                     duration:(NSTimeInterval)duration {
[self alignSubviews];
//NSLog(@"%f", currentPage * scrollView.bounds.size.width);
scrollView.contentOffset = CGPointMake(currentPage * scrollView.bounds.size.width, 0);
}

希望对大家有所帮助。

干杯。

- Nishant B

Answer 2

在UIScrollView中，每个页面都需要一个单独的UIViewController（PageViewController）吗？为什么不让您的MainViewController处理这个问题。

如果您在Interface Builder中构建UI，则在旋转设备后调整视图（和UI总体）大小要容易得多。

- Bart Jacobs

---

我看过那个会话视频，虽然它很有教育意义，但它根本没有处理旋转。我现在已经基本解决了我的问题，但由于解决方案很复杂，我没有在这里发布。 - jbrennan

Answer 3

我不确定我是否完全理解你的意思，但是有一些想法：

框架属性是一件事情（A），视图内容在其中显示的方式是另一件事情（B）。框架CGRect是您在父视图（superview）中视图的（理论上的）边界.. 但是，您的View不一定需要填充整个框架区域。

关于（A）： 在这里，我们有UIView的autoresizingMask属性，用于设置当父视图调整大小时如何调整框架大小。当您更改方向时会发生这种情况。但是，您通常可以依赖默认设置（到目前为止对我有效）。

关于（B）： 视图内容在视图框架中的分布由UIView的contentMode属性指定。使用此属性，您可以设置纵横比需要保持不变。例如将其设置为UIViewContentModeScaleAspectFit或其他内容。

看这里： http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIView_Class/UIView/UIView.html#//apple_ref/doc/uid/TP40006816-CH3-SW99 PS：我写了“理论上”，因为您的视图内容可能超出这些框架边界 - 它们仅在将UIView的clipsToBounds属性设置为YES时限制视图。我认为苹果默认设置为NO是一个错误。

- Efrain

Answer 4

除了Efrain所写的内容外，还要注意如果视图变换不是标识变换（即视图被旋转）则框架属性是无效的。

当然，您已经考虑到视图需要处于新的偏移位置了对吧？

- Olie

---

当视图的自身变换为标识时，帧属性在视图上是有效的。自动旋转功能在更深层次（可能是窗口）使用变换 - 在窗口上放置的滚动视图实际上不会改变其自身变换，因此可以毫无问题地使用帧属性。OP似乎没有更改滚动视图上的显式变换。 - Ben Zotto