是否可以在Objective-C（iphone）中使用JavaScript？

Question

如果可能，那麼我如何在我的代碼中使用JavaScript？

Answer 1

可以在UIWebView中注入JavaScript。

NSString * result = [myUIWebView stringByEvaluatingJavaScriptFromString:@"document.getElementById('foo').className"]; 

Answer 2

爲了增加j_freyre的回答，這表明你如何出來的Javascript從目標C執行並獲取數據，也可以從JavaScript調用在一個UIWebView運行目標C代碼。這需要多一點工作，並且有點冒險。

在JavaScript端：

var call_stack = new Array(); //This will hold our Objective C function calls 
function addWithObjC(a,b){ 
    call_stack.splice(0,0,"add:"+a+":"+b); //We separate the components of the call (function name, parameters) by a colon, but it could be anything. 
    window.location.href = "::ObjCcall::"; 
} 
function multiplyWithObjC(a,b){ 
    call_stack.splice(0,0,"multiply:"+a+":"+b); 
    window.location.href = "::ObjCcall::"; 
} 

這將嘗試加載一個虛假的URL。 「:: ObjCcall ::」可以是任何不是可能有效的url。現在的關鍵是要趕上目的C.申請假設你有一個UIWebView和相應的UIViewController，在UIViewController接口註明：

@interface MyWebViewController : UIViewController <UIWebViewDelegate>{ 
    //declare stuff 
} 

在實現方面，地方：

[(UIWebView *)self.view setDelegate:self]; 

你然後通過執行以下操作來捕獲請求：

- (BOOL) webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType 
{ 
    NSString *url = [[request URL] absoluteString]; //Our potentially bogus request url 
    if([url hasSuffix:@"::ObjCcall::"]){ //We're trying to call Objective C code 
    NSString *command; //Our specially formatted function call 
    //While our call stack is not empty... 
    while(![command = [webView stringByEvaluatingJavaScriptFromString:@"call_stack.pop()"]isEqualToString:@""]){ 
      //Break the function call into its compoments 
      NSArray *segments = [command componentsSeparatedByString:@":"]; 

      //We found a call we respond to 
      if(([[segments objectAtIndex:0] isEqualToString:@"add"])&&([segments count] > 2)){ 
       //Here is where the Objective C action takes place 
       float result = [[segments objectAtIndex:1]floatValue] + [[segments objectAtIndex:2]floatValue]; 
       //Do something with the results... 
      } 
      else if(([[segments objectAtIndex:0] isEqualToString:@"multiply"])&&([segments count] > 2)){ 
       //Another function 
       float result = [[segments objectAtIndex:1]floatValue] * [[segments objectAtIndex:2]floatValue]; 
      } 
      //Add more checks as needed 

      [segments release]; 

      return NO; //This tells the UIWebView to not try to load the page 
     } 
    } 
    else{ 
    return YES; //This is a valid URL request, load the page 
    } 
} 

這比看起來似乎有點複雜一點。但是，UIWebView並不喜歡連續快速更改window.location.href。我們實現一個調用堆棧以確保沒有呼叫被跳過。

設置比Objective C中的Javascript更多的工作，當然，一旦你設置了樣板，你需要做的就是在shouldStartLoadWithRequest中的while循環中添加檢查。