Question

我对如何在UIWebView中执行的js中提取var的值感到困惑，我的代码是：

NSString * js = [NSString stringWithFormat:@"var script = document.createElement('script');"  
                     "script.type = 'text/javascript';"  
                     "script.text = \"function getTopLeftCorner() { "  
                        "var el = document.elementFromPoint(%f, %f);"
                        "var pos = [el.offsetLeft, el.offsetTop];"
                        "var parent = el.offsetParent;"
                        "if (parent != el) {" 
                            "while (parent) {"  
                             "pos[0] += parent.offsetLeft;" 
                             "pos[1] += parent.offsetTop;" 
                             "parent = parent.offsetParent;"
                            "}"
                        "}"
                        "return pos;"
                      "}\";"  
                      "document.getElementsByTagName('head')[0].appendChild(script);"
                     , pt.x, pt.y];  

    [self stringByEvaluatingJavaScriptFromString:js];
    NSString * result = [self stringByEvaluatingJavaScriptFromString:@"getTopLeftCorner()"];

    NSLog(@"RESULT IS %@", result);

知道为什么结果是空的吗？

Answer 1

您的第一个语句NSString * js = [NSString stringWithFormat:@"var script会关闭该行末尾的字符串，然后再跟踪几个C strings。您应该从Objective-C编译器获得语法错误。

要连接字符串，请使用[NSString stringWithFormat:@"%@/%@/%@", three, two, one];。请仔细阅读class reference以获得有关该方法的更多说明。

在UIWebView中从JS返回var

1 个答案: