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我试图通过调用以下方法将一个推UIView到另一个上：UIViewUINavigationController

signupPageObj = [[SignupPage alloc]initWithNibName:@"SignupPage" bundle:nil];
[self.navigationController pushViewController:signupPageObj animated:YES];

但是加载我的 SignUpPage 时卡住了一段时间UIView。我不知道是什么原因，但因为我没有太多的自定义viewDidLoad和方法initWithNibName。

整个代码initWithNibName如下：

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

    if (self) 
    {
        statusArray=[[NSMutableArray alloc] init];
        UILabel *labelforNavigationTitle = [[UILabel alloc] initWithFrame:CGRectZero];
        labelforNavigationTitle.backgroundColor = [UIColor clearColor];
        labelforNavigationTitle.font = [UIFont fontWithName:FONTSAVINGSBOND size:30.0];
        labelforNavigationTitle.shadowColor = [UIColor colorWithWhite:0.0 alpha:0.5];
        labelforNavigationTitle.textAlignment = UITextAlignmentCenter;
        labelforNavigationTitle.textColor = [UIColor whiteColor]; // change this color
        self.navigationItem.titleView = labelforNavigationTitle;
        labelforNavigationTitle.text = NSLocalizedString(@"Sign Up", @"");
        [labelforNavigationTitle sizeToFit];

    }
    return self;

}


-(void)viewDidLoad
{

    [super viewDidLoad];

    self.fullPathToFile=@"";
    self.gender=@"";
    strForGender=self.gender;
    labelInDatePicker.font=[UIFont fontWithName:FONTCENTURYGOTHICBOLD size:17.0];


    UIImage* imageCancel = [UIImage imageNamed:@"cancelbtn.png"];
    CGRect frameimg = CGRectMake(0, 0, (imageCancel.size.width)/2, (imageCancel.size.height)/2);


    UIButton *cancelButton = [[UIButton alloc] initWithFrame:frameimg];
    [cancelButton setBackgroundImage:imageCancel forState:UIControlStateNormal];
    [cancelButton addTarget:self action:@selector(cancelButtonclickedInAvtar)
         forControlEvents:UIControlEventTouchUpInside];
    [cancelButton setShowsTouchWhenHighlighted:YES];



    self.pickerBirthdayView.frame=CGRectMake(0,460,320,252);
    [self.view addSubview:self.pickerBirthdayView];

    self.avtarView.frame=CGRectMake(0,460,320,460);
    [self.view addSubview:self.avtarView];
    cancelButtonInAvtarView=[[UIBarButtonItem alloc]initWithCustomView:cancelButton];

    self.termsAndConditionPage.frame=CGRectMake(0,460,320,460);
    [self.view addSubview:self.termsAndConditionPage];


    if ([self.navigationController.navigationBar respondsToSelector:@selector(setBackgroundImage:forBarMetrics:)] ) 
    {
        UIImage *image = [UIImage imageNamed:@"titlebg.png"] ;
        [self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
    }
    [self performSelector:@selector(settingScrollView) withObject:nil afterDelay:1.0];

    scrollPrevButton.hidden=YES;
    scrollNextButton.hidden=NO;

    isSectionExpanded=NO;
    checkForImage=2;
    termsAndConditionChecked=2;
    checkForBackgroundImage=10;
    start=10;


    UIImage* image1 = [UIImage imageNamed:@"backbtn.png"];
    CGRect frameimg1 = CGRectMake(0, 0, (image1.size.width)/2, (image1.size.height)/2);

    UIButton *backButton = [[UIButton alloc] initWithFrame:frameimg1];
    [backButton setBackgroundImage:image1 forState:UIControlStateNormal];
    [backButton addTarget:self action:@selector(popToRootViewController)
         forControlEvents:UIControlEventTouchUpInside];


    //    UIImage* image2 = [UIImage imageNamed:@"submitbtn.png"];
    //    CGRect frameimg2 = CGRectMake(0, 0, (image2.size.width)/2, (image2.size.height)/2);

    //    UIButton *submitButton = [[UIButton alloc] initWithFrame:frameimg2];
    //    [submitButton setBackgroundImage:image2 forState:UIControlStateNormal];
    //    [submitButton addTarget:self action:@selector(submitButtonPressed:)forControlEvents:UIControlEventTouchUpInside];


    UIImage* imageforTermsandConditionPage = [UIImage imageNamed:@"backbtn.png"];
    CGRect frameimgforTermsandConditionPage = CGRectMake(0, 0, (imageforTermsandConditionPage.size.width)/2, (imageforTermsandConditionPage.size.height)/2);

    UIButton *backButtonforTermsandConditionPage = [[UIButton alloc] initWithFrame:frameimgforTermsandConditionPage];
    [backButtonforTermsandConditionPage setBackgroundImage:imageforTermsandConditionPage forState:UIControlStateNormal];
    [backButtonforTermsandConditionPage addTarget:self action:@selector(backtoSignupPage) forControlEvents:UIControlEventTouchUpInside];



    UIImage* imageforChooseIconPage = [UIImage imageNamed:@"backbtn.png"];
    CGRect frameimgforChooseIconPage = CGRectMake(0, 0, (imageforChooseIconPage.size.width)/2, (imageforChooseIconPage.size.height)/2);

    UIButton *backButtonforChooseIconPage = [[UIButton alloc] initWithFrame:frameimgforChooseIconPage];
    [backButtonforChooseIconPage setBackgroundImage:imageforTermsandConditionPage forState:UIControlStateNormal];
    [backButtonforChooseIconPage addTarget:self action:@selector(backtoSignupPage) forControlEvents:UIControlEventTouchUpInside];



    backButton1 = [[UIBarButtonItem alloc] initWithCustomView:backButton];
    self.navigationItem.leftBarButtonItem = backButton1;

    //    submitButton1=[[UIBarButtonItem alloc]initWithCustomView:submitButton];
    //    self.navigationItem.rightBarButtonItem=submitButton1;

    backButtonInTermsAndCondition=[[UIBarButtonItem alloc]initWithCustomView:backButtonforTermsandConditionPage];
    backButtonInChooseIcon=[[UIBarButtonItem alloc]initWithCustomView:backButtonforChooseIconPage];


    CALayer *layer = [self.objTextView layer];
    [layer setMasksToBounds:YES];
    [layer setCornerRadius:10.0];
    [layer setBorderWidth:0.0];
    [layer setBorderColor:[[UIColor lightGrayColor] CGColor]];
}


-(void)settingScrollView
{
    arrOfImages=[NSArray arrayWithObjects:@"Avtar0.png",@"Avtar1.png",@"Avtar2.png",@"Avtar3.png",@"Avtar4.png",@"Avtar5.png",@"Avtar6.png",@"Avtar7.png",@"Avtar8.png",@"Avtar9.png",nil];

    pageControl.numberOfPages = kNumberOfPages;
    pageControl.currentPage = 0;
    pageControl = [[PageControl alloc] initWithFrame:rect] ;
    pageControl.frame = rect;
    pageControl.delegate=self;
    pageControl.numberOfPages=[arrOfImages count];
    pageControl.currentPage = self.currentPage;
    [self.view addSubview:pageControl];

    scrollV = [[UIScrollView alloc]init];
    scrollV.frame=CGRectMake(35,55,250,246);
    scrollV.backgroundColor=[UIColor clearColor];
    scrollV.delegate=self;
    scrollV.pagingEnabled=YES;
    self.scrollV.contentSize = CGSizeMake(self.scrollV.frame.size.width *kNumberOfPages, 220);

    self.scrollV.showsHorizontalScrollIndicator = NO;
    self.scrollV.showsVerticalScrollIndicator = NO;
    self.scrollV.scrollsToTop = NO;
    self.scrollV.delegate = self;

    [self.avtarView addSubview:scrollV];


    for(int k =0;k<arrOfImages.count;k++)
    {

        UIButton *btn=[UIButton  buttonWithType:UIButtonTypeCustom];
        btn.tag=k;
        btn.imageView.contentMode= UIViewContentModeScaleAspectFit;
        [btn setImage:[UIImage imageNamed:[arrOfImages objectAtIndex:k]] forState:UIControlStateNormal];
        [btn setImage:[UIImage imageNamed:[arrOfImages objectAtIndex:k]] forState:UIControlStateHighlighted];
         btn.frame=CGRectMake((self.scrollV.frame.size.width * k),0, 250,241);
        [btn addTarget:self action:@selector(setImageInScrollView:) forControlEvents:UIControlEventTouchUpInside];
        [self.scrollV addSubview:btn];
    }

}

如果有人对此有建议或解决方案，我将不胜感激。

4

1 回答 1

2

我注意到您settingScrollView正在加载一堆图像（特别是如果它们很大），这可能会很慢。这也是对内存的过度使用。这个问题有两种常见的解决方案：

  1. 您可以使用异步图像加载。除了在主队列中加载图像，您可以使用 GCD（或任何并发技术）在后台加载图像，然后将图像视图image属性的设置分派回主队列。这解决了性能问题，但没有解决内存问题。

  2. 更好的是，您可以使用延迟加载，仅加载当前可见图像的图像。然后将您的视图控制器配置为 aUIScrollViewDelegate并且当用户滚动到下一个图像时，然后加载它。您可以对此进行变体，加载当前图像和“下一个”图像，当用户滚动到下一个图像时，您会延迟加载新的“下一个”图像。大多数延迟加载技术也采用异步图像加载，这是我的第一个观察。

更新：

显然，如果您替换以下内容，您的屏幕演示将会得到改善：

[self performSelector:@selector(settingScrollView) withObject:nil afterDelay:1.0];

只需：

[self settingScrollView];

但我想你是因为某种原因延迟了那一秒。也许您不喜欢加载十张图像所花费的延迟，并且您不想因此减慢整个用户界面的速度。所以你可以使用我的第一个技术，图像的异步加载，在加载图像时不阻塞用户界面。如果你想这样做，你可以用类似的东西替换for循环：settingScrollView

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

for (int k = 0; k < arrOfImages.count; k++)
{
    UIButton *btn = [UIButton  buttonWithType:UIButtonTypeCustom];
    btn.tag = k;
    btn.imageView.contentMode = UIViewContentModeScaleAspectFit;
    dispatch_async(queue, ^{

        // retrieve the image in a background queue

        UIImage *image = [UIImage imageNamed:[arrOfImages objectAtIndex:k]];

        // and now update the image property in your UI in the main queue

        dispatch_async(dispatch_get_main_queue(), ^{
            [btn setImage:image forState:UIControlStateNormal];
            [btn setImage:image forState:UIControlStateHighlighted];

            btn.frame=CGRectMake((self.scrollV.frame.size.width * k),0, 250, 241);
            [btn addTarget:self action:@selector(setImageInScrollView:) forControlEvents:UIControlEventTouchUpInside];
            [self.scrollV addSubview:btn];
        });
    });
    // btn.frame=CGRectMake((self.scrollV.frame.size.width * k),0, 250, 241);
    // [btn addTarget:self action:@selector(setImageInScrollView:) forControlEvents:UIControlEventTouchUpInside];
    // [self.scrollV addSubview:btn];
}

话虽如此，图像的加载imageNamed通常并没有那么慢（尽管如果图像真的很大，它可能会引入一个可观察到的，如果适度的话，延迟）。但是上面的代码将进一步最小化从持久存储加载图像所带来的用户界面延迟。假设您的图像大约为 250x241，性能提升是适度的（当然，它返回到我的用户界面的速度是原来的十倍，但是因为同步加载图像只需要 0.05 秒，而异步加载它们，我的 UI 返回0.005 秒）。这种技术在拍摄真正平滑的 tableview 滚动时非常有用，或者如果从 web 加载图像，但不清楚它是否值得在这里（除非你的图像很大）。

我不会解决我的第二点，图像的延迟加载，除非你告诉我们你有内存问题。如果是这种情况，我们将用（因为这是一个非常粗糙的缓存系统）替换该imageNamed方法，并将其包装在适当的延迟加载方案中。但是只有十张图像，您可能不需要去那里。所以我会推迟那个解决方案，除非你回来告诉我们你有严重的记忆问题。imageWithContentsOfFileimageNamed

于 2013-01-18T16:41:11.030 回答