UIWebView本身不支持弹出窗口，然而有需求要用，不仅需要弹出窗口，而且需要在用户关闭窗口时触发一个javascript函数。研究了一下，没有使用任何第三方库实现了。
基本的思路是在UIWebView中拦截window.open和window.close的调用。这里有2个技术问题：
1.如何在objective-c中改变javascript的行为？
我的思路是在页面加载完之后注入javascript。简单的说就是webViewDidFinishLoad中使用UIWebView 的stringByEvaluatingJavaScriptFromString注入javascript代码。
2.如何用javasript调用objective-c代码？
我使用URLScheme的方式来做。简单的来说，就是让定义2个URLScheme:
open://:用来出发弹出窗口；
back://:用来关闭窗口；后面可以跟一个参数，触发window.close之后需要回调的javascript函数;
然后在- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType中拦截URL请求就可以调用objective-c代码了。
具体的相关代码如下：
1.ViewController实现UIWebViewDelegate，在ViewDidLoad中将UIWebView的delegate设为自己:
_browser.delegate = self;
2.webViewDidFinishLoad中注入javascript
-(void) webViewDidFinishLoad:(UIWebView*)webView {
// this is a pop-up window
if (wvPopUp)
{
NSString *js = @"window.close = function () {window.location.assign(\"back://\" + window.location);};";
__unused NSString *jsOverrides = [webView
stringByEvaluatingJavaScriptFromString:js];
}else {
///其他处理
NSString *js = @"window.open = function (url, d1, d2) { window.location = \"open://\" + url; }";
__unused NSString *jsOverrides = [webView
stringByEvaluatingJavaScriptFromString:js];
}
}
}
3.在shouldStartLoadWithRequest中拦截URL请求
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{
NSString* requestURL = request.URL.absoluteString;
if ([requestURL rangeOfString:@"back://"].location == 0)
{
[self closePopup];
return NO;
} else if ([requestURL hasPrefix: @"open://"]){
NSString *newUrl = [requestURL stringByReplacingOccurrencesOfString:@"open://" withString:@""];
NSURLRequest *newRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:newUrl]];
UIWebView *wv = [self popUpWebview];
[wv loadRequest:newRequest];
return NO;
}
return YES;
}
4.弹出窗口的objectie-c代码
- (UIWebView *) popUpWebview
{
// Create a web view that fills the entire window, minus the toolbar height
CGRect rect = CGRectMake(_browser.frame.origin.x+20,_browser.frame.origin.y+20,
_browser.frame.size.width-40,_browser.frame.size.height-40);
vwPopUpContainer = [[UIView alloc] initWithFrame: rect];
vwPopUpContainer.backgroundColor = [UIColor grayColor];
[self.view addSubview:vwPopUpContainer];
CGRect rectBtn = CGRectMake(10, 10, 60, 20);
btnClosePopup = [[UIButton alloc] initWithFrame:rectBtn];
[btnClosePopup setTitle:@"Close" forState:UIControlStateNormal];
[btnClosePopup addTarget:self action:@selector(closePopup) forControlEvents:UIControlEventTouchUpInside];
[vwPopUpContainer addSubview:btnClosePopup];
CGRect rectWeb = CGRectMake(10, 40, rect.size.width - 20, rect.size.height - 50);
UIWebView *webView = [[UIWebView alloc]
initWithFrame: rectWeb];
webView.scalesPageToFit = YES;
webView.delegate = self;
wvPopUp = webView;
[vwPopUpContainer addSubview:wvPopUp];
return webView;
}
5.关闭窗口处理包括回调触发带参数的javascript函数,这里函数名为onClosePopo
- (void) closePopup {
if (wvPopUp) {
NSURL *url = wvPopUp.request.URL;
NSString *surl = url.absoluteString;
NSUInteger pos = [surl rangeOfString:@"?"].location;
NSString *paras = @"";
if (pos != NSNotFound && pos < [surl length]-1) {
paras = [surl substringFromIndex:pos + 1];
}
NSString *js = [NSString stringWithFormat: @"onClosePopo('%@');",paras ];
__unused NSString *jsOverrides = [_browser
stringByEvaluatingJavaScriptFromString:js];
[wvPopUp removeFromSuperview];
wvPopUp = nil;
}
if(btnClosePopup){
[btnClosePopup removeFromSuperview];
btnClosePopup = nil;
}
if(vwPopUpContainer){
[vwPopUpContainer removeFromSuperview];
vwPopUpContainer = nil;
}
}
2017年2月27日更新
完整的演示例子已经上传到 github
