UIWebView

一、概覽（Overview）

1.支持的文件格式（Supported File Formats）

2.狀態(tài)保存（State Preservation）

3.關(guān)于繼承（Subclassing Notes）

二藏畅、職能（Tasks）

1.設(shè)置代理（Setting the Delegate）

• delegate

2.加載內(nèi)容（Loading Content）

• - loadData:MIMEType:textEncodingName:baseURL:
• - loadHTMLString:baseURL:
• - loadRequest:
• request
• loading
• - stopLoading
• - reload

3.后退前進（Moving Back and Forward）

• canGoBack
• canGoForward
• - goBack
• - goForward

4.內(nèi)容相關(guān)屬性的設(shè)置（Setting Web Content Properties）

• allowsLinkPreview
• scalesPageToFit
• scrollView
• suppressesIncrementalRendering
• keyboardDisplayRequiresUserAction
• dataDetectorTypes

5.調(diào)用 JavaScript（Running JavaScript）

• - stringByEvaluatingJavaScriptFromString:

6.多媒體播放（Managing Media Playback）

• allowsInlineMediaPlayback
• mediaPlaybackRequiresUserAction
• mediaPlaybackAllowsAirPlay
• allowsPictureInPictureMediaPlayback

7.頁面設(shè)置（Managing Pages）

• gapBetweenPages
• pageCount
• pageLength
• paginationBreakingMode
• paginationMode

8.廢棄的屬性（Deprecated Properties）

• detectsPhoneNumbers

三鹰晨、數(shù)據(jù)類型（Data Types）

• UIWebViewNavigationType

四马绝、常量（Constants）

• UIWebPaginationBreakingMode
• UIWebPaginationMode

五阳准、文檔修訂記錄（Document Revision History）

UIWebView 參考文檔（ UIWebView Class Reference ）

繼承鏈：UIView : UIResponder : NSObject

遵守協(xié)議：
NSCoding源请，NSObject，UIAppearance铲球，UIAppearanceContainer挺庞，UICoordinateSpace，UIDynamicItem稼病，UIFocusEnvironment选侨，UIScrollViewDelegate，UITraitEnvironment

框架導(dǎo)入：@import UIKit;

適用范圍：iOS 2.0 and later

相關(guān)文檔：UIKit User Interface Catalog, Text Programming Guide for iOS

你可以用 UIWebView 來將網(wǎng)頁（web content）嵌入到你的 app 中然走。怎么實現(xiàn)呢援制？首先創(chuàng)建一個 UIWebView 對象，添加到一個 window 上芍瑞， 然后給它發(fā)送一個請求去加載網(wǎng)頁（web content）晨仑。你還可以用這個類在網(wǎng)頁瀏覽記錄中后退前進（move back and forward），甚至可以設(shè)置一些網(wǎng)頁屬性（web content properties）拆檬。

說明：在只支持iOS 8及以后的系統(tǒng)的 app 中洪己，建議使用 WKWebView，而不是 UIWebView 竟贯。值得注意的一點是答捕，如果你要渲染的文件不支持運行 JavaScript 的話，不妨將 WKPreferences 的 javaScriptEnabled 屬性設(shè)為 NO屑那。

我們可以使用 loadHTMLString:baseURL: 方法來加載本地 HTML 文件或者用 loadRequest: 方法來加載網(wǎng)頁（web content）拱镐。我們還可以通過調(diào)用 stopLoading 方法來停止加載，以及通過獲取屬性 loading 的值來判斷一個 web view 是否還處于正在加載的過程中持际。

如果你想讓用戶在瀏覽網(wǎng)頁時可以前進后退沃琅，你可以通過 button 的 action 對 goBack 和 goForward 方法的調(diào)用來控制。當(dāng)用戶不能在某一個方向“移動”時选酗，需要使用 canGoBack 和 canGoForward 屬性來禁用按鈕的前進后退操作阵难。

默認情況下，一個 web view 會自動將網(wǎng)頁中的電話號碼轉(zhuǎn)成一個號碼鏈接（Phone links）芒填。當(dāng)用戶在點擊那個鏈接（Phone links）時呜叫，系統(tǒng)會自動啟動 Phone app 并撥打那個電話號碼。你可以將屬性dataDetectorTypes 的值設(shè)置為一個 UIDataDetectorTypes 位字段來關(guān)閉這個電話號碼識別行為殿衰，因為UIDataDetectorTypes不包括 UIDataDetectorTypePhoneNumber 這個標(biāo)志位朱庆。

你可以通過設(shè)置 scalesPageToFit 屬性來設(shè)置網(wǎng)頁（web content）第一次展示在一個 web view 中的頁面比例。但僅僅這個屬性只在首次展示時有效闷祥，首次展示之后用戶仍然可以通過手勢改變頁面比例娱颊。

如果你想追蹤網(wǎng)頁內(nèi)容（web content）的加載傲诵，你需要將 web view 的 delegate 屬性賦給一個遵守 UIWebViewDelegate 協(xié)議的對象。

重要：不要將 UIWebView 或 UITableView 對象嵌入到 UIScrollView 對象中箱硕。如果你這么做了拴竹，將會導(dǎo)致一些意想不到的結(jié)果，因為那兩個嵌套的 view 的 touch 事件會被混淆并且會被錯誤地處理剧罩。

借助 Web Inspector栓拜，可以很方便地調(diào)試一個 UIWebView 中的HTML，CSS 和 JavaScript惠昔。你可以通過閱讀 Debugging Web Content on iOS 來學(xué)習(xí)如何配置 Web Inspector for iOS幕与。你還可以通過閱讀 Safari Web Content Guide 的其余部分，來學(xué)習(xí)如何創(chuàng)建一個為 iPhone 和 iPad 上的 Safari 而優(yōu)化的網(wǎng)頁（web content）镇防。

如果你想了解一些關(guān)于基本的 view 的知識啦鸣，不妨看一下View Programming Guide for iOS 。

一来氧、概覽（Overview）

1.支持的文件格式（Supported File Formats）

除了 HTML 內(nèi)容之外诫给，UIWebView 對象還可以被用來展示其他格式的內(nèi)容，比如饲漾，Keynote蝙搔，PDF，Pages文件等考传。為了能夠保證文本（plain and rich text）渲染的最佳效果吃型，建議使用 UITextView。

2.狀態(tài)保存（State Preservation）

在iOS 6及以后版本的系統(tǒng)中僚楞，如果你給 web view 的 restorationIdentifier 屬性賦一個值勤晚，它將會為每一頁保存它的 URL 歷史，縮放比例和滾動位置泉褐，以及當(dāng)前正在查看的網(wǎng)頁信息赐写。在恢復(fù)（ restoration）過程中，那個 view 會復(fù)原（ restore）這些值膜赃，因此那個網(wǎng)頁（web content）看起來就像它之前的樣子一樣挺邀。如果你想了解更多關(guān)于狀態(tài)保存和恢復(fù)是如何運作的信息，不妨讀一讀 App Programming Guide for iOS跳座。

更多關(guān)于外觀和行為配置的信息端铛，請看 Web Views。

3.關(guān)于繼承（Subclassing Notes）

UIWebView 不應(yīng)該被繼承疲眷。（The UIWebView class should not be subclassed. ）

二禾蚕、職能（Tasks）

1.設(shè)置代理（Setting the Delegate）

delegate Property

The receiver’s delegate.

Declaration

    @property(nonatomic, assign) id< UIWebViewDelegate > delegate 

Discussion
The delegate is sent messages when content is loading. See UIWebViewDelegate Protocol Reference for the optional methods this delegate may implement.

重要
在釋放一個你已經(jīng)為其設(shè)過 delegate 的 UIWebView 實例之前，你首先一定要將該 UIWebView 對象的 delegate 屬性設(shè)為 nil狂丝。比如說换淆，你可以在你的 dealloc 方法中這樣做哗总。

Important
Before releasing an instance of UIWebView for which you have set a delegate, you must first set its delegate property to nil
. This can be done, for example, in your dealloc method.

Availability
Available in iOS 2.0 and later.

2.加載內(nèi)容（Loading Content）

- loadData:MIMEType:textEncodingName:baseURL:

Sets the main page contents, MIME type, content encoding, and base URL.

Declaration

    - (void)loadData:(NSData *)data
            MIMEType:(NSString *)MIMEType
    textEncodingName:(NSString *)encodingName
             baseURL:(NSURL *)baseURL

Parameters

Availability
Available in iOS 2.0 and later.

See Also
- loadHTMLString:baseURL:

- loadHTMLString:baseURL:

Sets the main page content and base URL.

Declaration

    - (void)loadHTMLString:(NSString *)string
                   baseURL:(NSURL *)baseURL

Parameters

Discussion
To help you avoid being vulnerable to security attacks, be sure to use this method to load local HTML files; don’t use loadRequest:.

Availability
Available in iOS 2.0 and later.

See Also
- loadData:MIMEType:textEncodingName:baseURL:

- loadRequest:

Connects to a given URL by initiating an asynchronous client request.

Declaration

    - (void)loadRequest:(NSURLRequest *)request

Parameters

Discussion
Don’t use this method to load local HTML files; instead, use loadHTMLString:baseURL:. To stop this load, use the stopLoading method. To see whether the receiver is done loading the content, use the loading property.

Availability
Available in iOS 2.0 and later.

See Also
request
- stopLoading
loading
- reload

request Property

The URL request identifying the location of the content to load. (read-only)

Declaration

    @property(nonatomic, readonly, strong) NSURLRequest *request

Availability
Available in iOS 2.0 and later.

See Also
- loadRequest:
- stopLoading
loading
- reload

loading Property

A Boolean value indicating whether the receiver is done loading content. (read-only)

Declaration

    @property(nonatomic, readonly, getter=isLoading) BOOL loading

Discussion
If YES, the receiver is still loading content; otherwise, NO.

Availability
Available in iOS 2.0 and later.

See Also
request
- stopLoading
- loadRequest:
- reload

- stopLoading

Stops the loading of any web content managed by the receiver.

Declaration

     - (void)stopLoading

Discussion
Stops any content in the process of being loaded by the main frame or any of its children frames. Does nothing if no content is being loaded.

Availability
Available in iOS 2.0 and later.

See Also
request
loading
– loadRequest:
– reload

- reload

Reloads the current page.

Declaration

    - (void)reload

Availability
Available in iOS 2.0 and later.

See Also
request
loading
– loadRequest:
– stopLoading

3.后退前進（Moving Back and Forward）

canGoBack Property

A Boolean value indicating whether the receiver can move backward. (read-only)

Declaration

    @property(nonatomic, readonly, getter=canGoBack) BOOL canGoBack

Discussion
If YES, able to move backward; otherwise, NO.

Availability
Available in iOS 2.0 and later.

See Also
canGoForward

canGoForward Property

A Boolean value indicating whether the receiver can move forward. (read-only)

Declaration

       @property(nonatomic, readonly, getter=canGoForward) BOOL canGoForward

Discussion
If YES, able to move forward; otherwise, NO.

Availability
Available in iOS 2.0 and later.

See Also
canGoBack

- goBack

Loads the previous location in the back-forward list.

Declaration

     - (void)goBack

Availability
Available in iOS 2.0 and later.

See Also
– goForward

- goForward

Loads the next location in the back-forward list.

Declaration

     - (void)goForward

Availability
Available in iOS 2.0 and later.

See Also
– goBack

4.內(nèi)容相關(guān)屬性的設(shè)置（Setting Web Content Properties）

allowsLinkPreview Property

A Boolean value that determines whether pressing on a link displays a preview of the destination for the link.

Declaration

      @property(nonatomic) BOOL allowsLinkPreview

Discussion
This property is available on devices that support 3D Touch. Default value is NO.
If you set this value to YES for a web view, users (with devices that support 3D Touch) can preview link destinations, and can preview detected data such as addresses, by pressing on links. Such previews are known to users as peeks. If a user presses deeper, the preview navigates (or pops, in user terminology) to the destination. Because pop navigation switches the user from your app to Safari, it is opt-in, by way of this property, rather default behavior for this class.
If you want to support link preview but also want to keep users within your app, you can switch from using the UIWebView class to the SFSafariViewController class. If you are using a web view as an in-app browser, making this change is best practice. The Safari view controller class automatically supports link previews.

Availability
Available in iOS 9.0 and later.

scalesPageToFit Property

A Boolean value determining whether the webpage scales to fit the view and the user can change the scale.

Declaration

    @property(nonatomic) BOOL scalesPageToFit

Discussion
If YES, the webpage is scaled to fit and the user can zoom in and zoom out. If NO, user zooming is disabled. The default value is NO.

Availability
Available in iOS 2.0 and later.

scrollView Property

The scroll view associated with the web view. (read-only)

Declaration

      @property(nonatomic, readonly, strong) UIScrollView *scrollView

Discussion
Your app can access the scroll view if it wants to customize the scrolling behavior of the web view.

Availability
Available in iOS 5.0 and later.

suppressesIncrementalRendering Property

A Boolean value indicating whether the web view suppresses content rendering until it is fully loaded into memory.

Declaration

     @property(nonatomic) BOOL suppressesIncrementalRendering

Discussion
When set to YES, the web view does not attempt to render incoming content as it arrives. Instead, the view’s current contents remain in place until all of the new content has been received, at which point the new content is rendered. This property does not affect the rendering of content retrieved after a frame finishes loading.
The value of this property is NO by default.

Availability
Available in iOS 6.0 and later.

keyboardDisplayRequiresUserAction Property

A Boolean value indicating whether web content can programmatically display the keyboard.

Declaration

     @property(nonatomic) BOOL keyboardDisplayRequiresUserAction

Discussion
When this property is set to YES, the user must explicitly tap the elements in the web view to display the keyboard (or other relevant input view) for that element. When set to NO, a focus event on an element causes the input view to be displayed and associated with that element automatically.
The default value for this property is YES.

Availability
Available in iOS 6.0 and later.

dataDetectorTypes Property

The types of data converted to clickable URLs in the web view’s content.

Declaration

     @property(nonatomic) UIDataDetectorTypes dataDetectorTypes

Discussion
Use this property to specify the types of data (phone numbers, HTTP links, email address, and so on) that should be automatically converted to clickable URLs in the web view. When clicked, the web view opens the app responsible for handling the URL type and passes it the URL.
See the UIDataDetectorTypes enumeration for the types of data available for automatic detection.

Availability
Available in iOS 3.0 and later.

5.調(diào)用 JavaScript（Running JavaScript）

- stringByEvaluatingJavaScriptFromString:

Returns the result of running a JavaScript script. Although this method is not deprecated, best practice is to use the evaluateJavaScript:completionHandler: method of the WKWebView class instead.

Declaration

    - (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script

Parameters

Return Value
The result of running the JavaScript script passed in the script parameter, or nil if the script fails.

Discussion
New apps should instead use the evaluateJavaScript:completionHandler:
method from the WKWebView class. Legacy apps should adopt that method if possible.

IMPORTANT
The stringByEvaluatingJavaScriptFromString: method waits synchronously for JavaScript evaluation to complete. If you load web content whose JavaScript code you have not vetted, invoking this method could hang your app. Best practice is to adopt the WKWebView class and use its evaluateJavaScript:completionHandler: method instead.

Availability
Available in iOS 2.0 and later.

6.多媒體播放（Managing Media Playback）

allowsInlineMediaPlayback Property

A Boolean value that determines whether HTML5 videos play inline or use the native full-screen controller.

Declaration

     @property(nonatomic) BOOL allowsInlineMediaPlayback

Discussion
The default value on iPhone is NO.
In order for video to play inline, not only does this property need to be set on the view, but the video element in the HTML document must also include the webkit-playsinline attribute.

Availability
Available in iOS 4.0 and later.

mediaPlaybackRequiresUserAction Property

A Boolean value that determines whether HTML5 videos can play automatically or require the user to start playing them.

Declaration

     @property(nonatomic) BOOL mediaPlaybackRequiresUserAction

Discussion
The default value on both iPad and iPhone is YES . To make media play automatically when loaded, set this property to NO and ensure the <audio> or <video> element you want to play has the autoplay attribute set.

Availability
Available in iOS 4.0 and later.

mediaPlaybackAllowsAirPlay Property

A Boolean value that determines whether Air Play is allowed from this view.

Declaration

    @property(nonatomic) BOOL mediaPlaybackAllowsAirPlay

Discussion
The default value on both iPad and iPhone is YES.

Availability
Available in iOS 5.0 and later.

allowsPictureInPictureMediaPlayback Property

A Boolean value that determines whether Picture in Picture playback is allowed from this view.

Declaration

      @property(nonatomic) BOOL allowsPictureInPictureMediaPlayback

Discussion
The default value is YES on devices that support Picture in Picture (PiP) mode and NO on all other devices.

Availability
Available in iOS 9.0 and later.

7.頁面設(shè)置（Managing Pages）

gapBetweenPages Property

The size of the gap, in points, between pages.

Declaration

    @property(nonatomic) CGFloat gapBetweenPages

Discussion
The default value is 0.

Availability
Available in iOS 7.0 and later.

pageCount Property

The number of pages produced by the layout of the web view. (read-only)

Declaration

     @property(nonatomic, readonly) NSUInteger pageCount

Availability
Available in iOS 7.0 and later.

pageLength Property

The size of each page, in points, in the direction that the pages flow.

Declaration

    @property(nonatomic) CGFloat pageLength

Discussion
When paginationMode is right to left or left to right, this property represents the width of each page. When paginationMode is top to bottom or bottom to top, this property represents the height of each page.
The default value is 0, which means the layout uses the size of the viewport to determine the dimensions of the page. Adjusting the value of this property causes a relayout.

Availability
Available in iOS 7.0 and later.

paginationBreakingMode Property

The manner in which column- or page-breaking occurs.

Declaration

     @property(nonatomic) UIWebPaginationBreakingMode paginationBreakingMode

Discussion
This property determines whether certain CSS properties regarding column- and page-breaking are honored or ignored. When this property is set to UIWebPaginationBreakingModeColumn
, the content respects the CSS properties related to column-breaking in place of page-breaking.
See UIWebPaginationBreakingMode for possible values. The default value isUIWebPaginationBreakingModePage.

Availability
Available in iOS 7.0 and later.

paginationMode Property

The layout of content in the web view.

Declaration

     @property(nonatomic) UIWebPaginationMode paginationMode

Discussion
This property determines whether content in the web view is broken up into pages that fill the view one screen at a time, or shown as one long scrolling view. If set to a paginated form, this property toggles a paginated layout on the content, causing the web view to use the values of pageLength and gapBetweenPages
to relayout its content.
See UIWebPaginationMode for possible values. The default value is UIWebPaginationModeUnpaginated.

Availability
Available in iOS 7.0 and later.

8.廢棄的屬性（Deprecated Properties）

detectsPhoneNumbers (iOS 3.0) Property

三、數(shù)據(jù)類型（Data Types）

UIWebViewNavigationType

Constant indicating the user’s action.

Declaration

enum { UIWebViewNavigationTypeLinkClicked,     // User tapped a link. Available in iOS 2.0 and later.
       UIWebViewNavigationTypeFormSubmitted,   // User submitted a form. Available in iOS 2.0 and later.
       UIWebViewNavigationTypeBackForward,     // User tapped the back or forward button. Available in iOS 2.0 and later.
       UIWebViewNavigationTypeReload,          // User tapped the reload button. Available in iOS 2.0 and later.
       UIWebViewNavigationTypeFormResubmitted, // User resubmitted a form. Available in iOS 2.0 and later.
       UIWebViewNavigationTypeOther            // Some other action occurred. Available in iOS 2.0 and later.
};
typedef NSUInteger UIWebViewNavigationType;

Import Statement

@import UIKit;

Availability
Available in iOS 2.0 and later.

四倍试、常量（Constants）

UIWebPaginationBreakingMode

The manner in which column- or page-breaking occurs.

Declaration

typedef NS_ENUM (NSInteger, UIWebPaginationBreakingMode ) { 
   UIWebPaginationBreakingModePage,   // Content respects CSS properties related to page-breaking. Available in iOS 7.0 and later.
   UIWebPaginationBreakingModeColumn  // Content respects CSS properties related to column-breaking. Available in iOS 7.0 and later.
};

Import Statement

@import UIKit;

Availability
Available in iOS 7.0 and later.

UIWebPaginationMode

The layout of content in the web view, which determines the direction that the pages flow.

Declaration

typedef NS_ENUM (NSInteger, UIWebPaginationMode ) { 
   UIWebPaginationModeUnpaginated,   // Content appears as one long scrolling view with no distinct pages. Available in iOS 7.0 and later.
   UIWebPaginationModeLeftToRight,   // Content is broken up into pages that flow from left to right. Available in iOS 7.0 and later.
   UIWebPaginationModeTopToBottom,   // Content is broken up into pages that flow from top to bottom. Available in iOS 7.0 and later.
   UIWebPaginationModeBottomToTop,   // Content is broken up into pages that flow from bottom to top. Available in iOS 7.0 and later.
   UIWebPaginationModeRightToLeft    // Content is broken up into pages that flow from right to left. Available in iOS 7.0 and later.
};

五讯屈、文檔修訂記錄（Document Revision History）

下表中列出了文檔 *UIWebView Class Reference * 的變化。

英文版

參考（Reference）： https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIWebView_Class/