Question

我对XCode还不熟悉 - 我正在设计一个带有单一视图的应用程序，它只显示一个加载我的jQuery移动网站的UIWebView。

我有适用于启动图像的Default.png和Default@2x.png文件。当我在我的测试设备或模拟器中运行应用程序时，它会显示我的启动图像，然后在UIWebView加载第一页时闪烁白屏。

我知道我可以改变背景颜色和不透明度，因此它会闪烁不同于白色的颜色，但我想完全阻止闪光。我希望应用程序启动，显示启动图像，并且在第一页完全加载之前不显示UIWebView。帮助

Answer 1

@ Andreas Volz（以及其他任何想知道我是如何解决白色“闪光”问题的人）

首先，将name-of-loading-image.png和name-of-loading-image@2x.png文件添加到Xcode项目中。常规图像应为320 x 460，@2x图像应为640 x 920。

然后，在我的ViewController.h文件中，我添加了以下属性：

@property (nonatomic, retain) UIWebView *webView;
@property(nonatomic, strong) UIImageView *loadingImageView;
@end

然后在我的ViewController.m文件中我添加了这个：

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController;

@synthesize webView;
@synthesize loadingImageView;

- (void)viewDidLoad
{
    [super viewDidLoad];


    //**************** Set website URL for UIWebView
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.example.com"] cachePolicy:NSURLCacheStorageAllowed timeoutInterval:20.0]];


    //**************** Add Static loading image to prevent white "flash" ****************/  
    UIImage *loadingImage = [UIImage imageNamed:@"name-of-loading-image.png"];
    loadingImageView = [[UIImageView alloc] initWithImage:loadingImage];
        loadingImageView.animationImages = [NSArray arrayWithObjects:
                                            [UIImage imageNamed:@"name-of-loading-image.png"],
                                            nil];
    [self.view addSubview:loadingImageView];   

}

- (void)webViewDidFinishLoad:(UIWebView *)webView {

    // Remove loading image from view
    [loadingImageView removeFromSuperview];

}

Answer 2

要知道webView何时完成加载，您必须实现UIWebViewDelegate协议。

在viewController的.h文件中：

@interface viewController : UIViewController <UIWebViewDelegate>
{
    UIWebView *webView;
}
@end

然后在viewController的.m文件中添加以下方法：

- (void)webViewDidFinishLoad:(UIWebView *)webView {

    NSLog(@"content loading finished");
    // Display your webView
    [self.view addSubview:webView];

}

您可以在viewController的.m中使用-viewDidLoad方法继续显示启动图像。您也可以开始加载webView的内容：

- (void)viewDidLoad {
    [super viewDidLoad];

    // continue to display launch image
    UIImage *launchImage = [[UIImage alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"launchImage.png" ofType:nil ]];
    UIImageView *launchImageView = [[[UIImageView alloc] initWithImage:launchImage] autorelease];
    [self.view addSubview:launchImageView];

    // now setup the base view for the webView controller
    UIView *contentView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
    contentView.backgroundColor = [UIColor blueColor];

    // for rotation
    contentView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
    self.view = contentView;

    //create a frame to size and place the web view
    CGRect webFrame = [[UIScreen mainScreen] applicationFrame];
    UIWebView *aWebView = [[UIWebView alloc] initWithFrame:webFrame];
    self.webView = aWebView;

    //aWebView.scalesPageToFit = YES;
    aWebView.autoresizesSubviews = YES;
    aWebView.autoresizingMask=(UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth);

    //set the web view delegates for the web view to be itself
    [aWebView setDelegate:self];

    //determine the path the to the index.html file in the Resources directory
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"index" withExtension:@"html"];
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
    [aWebView loadRequest:requestObj];
}

启动图像后，XCode阻止UIWebView闪烁白屏

2 个答案: