iOS中 UIWebView加载网络数据 技术分享

直奔核心:

#import "TechnologyDetailViewController.h"
#define kScreenWidth [UIScreen mainScreen].bounds.size.width
#define kScreenHeight [UIScreen mainScreen].bounds.size.height
@interface TechnologyDetailViewController ()
@property (nonatomic,retain)UIWebView *webView;//显示详情页面
@end

@implementation TechnologyDetailViewController
- (void)dealloc
{
    self.webView = nil;
    self.ids = nil;
    [super dealloc];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    //设置背景
    self.view.backgroundColor = [UIColor yellowColor];
    //调用请求网络数据
    [self readDataFromNetWork];
    //    self.automaticallyAdjustsScrollViewInsets = NO;
    [self.view addSubview:self.webView];
}

懒加载UIWebView

//懒加载
- (UIWebView *)webView{
    if (!_webView) {
        self.webView = [[[UIWebView alloc]initWithFrame:CGRectMake(0,0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)]autorelease];
        self.webView.backgroundColor = [UIColor orangeColor];

    }
    return [[_webView retain ]autorelease];
}

核心代码如下:

//解析数据
- (void)readDataFromNetWork{
    NSString *str = [NSString stringWithFormat:@"http://c.3g.163.com/nc/article/%@/full.html",self.ids];
    NSURL *url = [NSURL URLWithString:str];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
        NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

        NSString *body = dic[self.ids][@"body"];
        NSString * title = dic[self.ids][@"title"];
        NSString *digest = dic[self.ids][@"digest"];
        NSString *ptime = dic[self.ids][@"ptime"];
        NSString * source = dic[self.ids][@"source"];
        NSArray * img = dic[self.ids][@"img" ] ;
        //        NSLog(@"%@",img);
        if (img.count) {
            for (int i = 0; i < img.count; i ++) {

                NSString *imgString = [NSString stringWithFormat:@"<p style=\"text-align:center\"><img src=\"%@\" /></p>",img[i][@"src"]];
                NSLog(@"imString  = %@",imgString);

                imgString = [imgString stringByReplacingOccurrencesOfString:@"<!--IMG#%d-->" withString:imgString];
                body = [imgString stringByAppendingString:body];

            }
        }
        //        NSLog(@"body =  %@",body);

        //借助第三方进行排版
        NSString *filePath = [[NSBundle mainBundle]pathForResource:@"topic_template" ofType:@"html"];
        NSString *htmlString = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];

        htmlString = [htmlString stringByReplacingOccurrencesOfString:@"__BODY__" withString:body];
        htmlString = [htmlString stringByReplacingOccurrencesOfString:@"__TITLE__" withString:title];
        htmlString = [htmlString stringByReplacingOccurrencesOfString:@"__AUTHOR__" withString:source];
        htmlString = [htmlString stringByReplacingOccurrencesOfString:@"__DIGEST__" withString:digest];
        htmlString = [htmlString stringByReplacingOccurrencesOfString:@"__TIME__" withString:ptime];
        htmlString = [htmlString stringByReplacingOccurrencesOfString:@"__PTIME__" withString:ptime];
        [self.webView loadHTMLString:htmlString baseURL:nil];

    }];

}

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

实在看不懂再看下demol例子:

UIWebView的loadRequest可以用来加载一个url地址，它需要一个NSURLRequest参数。我们定义一个方法用来加载url。在UIWebViewDemoViewController中定义下面方法：

- (void)loadWebPageWithString:(NSString*)urlString
{
    NSURL *url =[NSURL URLWithString:urlString];
    NSLog(urlString);
    NSURLRequest *request =[NSURLRequest requestWithURL:url];
    [webView loadRequest:request];
}

在界面上放置3个控件，一个textfield、一个button、一个uiwebview，布局如下：

在代码中定义相关的控件：webView用于展示网页、textField用于地址栏、activityIndicatorView用于加载的动画、buttonPress用于按钮的点击事件。

@interface UIWebViewDemoViewController :UIViewController<UIWebViewDelegate> {
    IBOutlet UIWebView *webView;
    IBOutlet UITextField *textField;
    UIActivityIndicatorView *activityIndicatorView;

}
- (IBAction)buttonPress:(id) sender;
- (void)loadWebPageWithString:(NSString*)urlString;
@end

使用IB关联他们。

设置UIWebView，初始化UIActivityIndicatorView：

- (void)viewDidLoad
{
    [super viewDidLoad];
    webView.scalesPageToFit =YES;
    webView.delegate =self;
    activityIndicatorView = [[UIActivityIndicatorView alloc]
                             initWithFrame : CGRectMake(0.0f, 0.0f, 32.0f, 32.0f)] ;
    [activityIndicatorView setCenter: self.view.center] ;
    [activityIndicatorView setActivityIndicatorViewStyle: UIActivityIndicatorViewStyleWhite] ;
    [self.view addSubview : activityIndicatorView] ;
    [self buttonPress:nil];
    // Do any additional setup after loading the view from its nib.
}

UIWebView主要有下面几个委托方法：

1、- (void)webViewDidStartLoad:(UIWebView *)webView;开始加载的时候执行该方法。

2、- (void)webViewDidFinishLoad:(UIWebView *)webView;加载完成的时候执行该方法。

3、- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error;加载出错的时候执行该方法。

我们可以将activityIndicatorView放置到前面两个委托方法中。

- (void)webViewDidStartLoad:(UIWebView *)webView
{
    [activityIndicatorView startAnimating] ;
}
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    [activityIndicatorView stopAnimating];
}

buttonPress方法很简单，调用我们开始定义好的loadWebPageWithString方法就行了：

- (IBAction)buttonPress:(id) sender
{
    [textField resignFirstResponder];
    [self loadWebPageWithString:textField.text];

}

当请求页面出现错误的时候，我们给予提示：

- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{
    UIAlertView *alterview = [[UIAlertView alloc] initWithTitle:@"" message:[error localizedDescription]  delegate:nil cancelButtonTitle:nil otherButtonTitles:@"OK", nil];
    [alterview show];
    [alterview release];
}

总结：本文通过实现一个简单的浏览器，说明了uiwebview的方法和属性，相信通过这个例子，应该明白uiwebview的使用了。

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