iOS 小技能：app嵌入H5页面的通用模版

前言

Avoiding iOS bug:UIWebView with file input doesn‘t work in modal view controller

• 从CSDN下载demo https://download.csdn.net/download/u011018979/15133282

https://github.com/zhangkn/KNUIWebViewWithFileInput.git

• 应用场景:modal UIWebView and camera/image picker

由于苹果模态的特性，当模态出N个ViewController之后，只需要dismiss任意一个，都会dismiss它之后的所有模态试图 。因此特性会导致的问题：modal模态出来的UIViewControllerWebView的H5弹出Camera/ImagePicker 时，当UIDocumentMenuViewController消失的时候会导致WebView 所在的控制器也被干掉。

• 解决思路:使dismissViewControllerAnimated调用一次，或者让UIDocumentMenuViewController找不到presentingViewController

基础概念: 1、presentedViewController ：The view controller that is presented by this view controller, or one of its ancestors in the view controller hierarchy. 2、presentingViewController：The view controller that presented this view controller (or its farthest ancestor.)

I 解决WebVC调摄像头之后，dismiss掉的问题

解决包含WebView的控制器调摄像头之后被UIDocumentMenuViewController干掉的问题

1.1 问题分析

UIDocumentMenuViewController 消失时调用的不仅调用了自己的，dismissViewControllerAnimated，还调用了，上层或者上上层presentingViewController的dismissViewControllerAnimated。即会循环调用modal 方式的个个层级的dismissViewControllerAnimated，让所有的控制器消失。因此当用户选择takePhoto或者photoLibrary的时候，会导致被modal出来的webView 所在的控制器也会销毁。

1.2 问题解决思路

只让UIDocumentMenuViewController 对象调用自己的dismissViewControllerAnimated，或者让UIDocumentMenuViewController找不到presentingViewController即可。

II 解决方案

2.1 方案1:只让UIDocumentMenuViewController 对象调用自己的dismissViewControllerAnimated方法

• 只让UIDocumentMenuViewController 对象调用自己的dismissViewControllerAnimated，不让加载H5 网页的控制器被刚掉（推荐使用此方法）

当前ViewController的所有presentedViewController都正常执行dismissViewControllerAnimated，当前ViewController本身执行dismissViewControllerAnimated，不进行dismiss，不做处理。

除非用户自己要求退出self.exitKNBaseWebViewControllerflagged = yes 或者 当想dismiss掉当前ViewController的时候，不能调用本身的dismissViewControllerAnimated ，直接调用父类的dismissViewControllerAnimated

重写拥有web View控制器的dismiss 方法

#if 1
 
-(void)dismissViewControllerAnimated:(BOOL)flag completion:(void (^)(void))completion
 
{
 
    /**presentedViewController   本控制器即将present展示的控制器
 
      
 
     思路，第一次 UIDocumentMenuViewController 展示拍照和photo界面的控制器 消失
 
     第二次    self.presentedViewController nil  此时不调用dismissViewControllerAnimated,, 如果自己要消失的话，需要新增个标识，表示是用户要返回
 
      
 
     第三次 UIImagePickerController  相册、拍照控制器 消失
 
      
 
     */
 
     
 
    if ( self.presentedViewController )
 
    {
 
        [super dismissViewControllerAnimated:flag completion:completion];
 
    }
 
     
 
//    if (self.exitKNBaseWebViewControllerflagged) {
 
//        self.exitKNBaseWebViewControllerflagged = NO;
 
//        [super dismissViewControllerAnimated:flag completion:completion];
 
//    }
 
     
 
}
 
#endif

2.2 方案2：使UIDocumentMenuViewController找不到presentingViewController

解决方法就是不让UIDocumentMenuViewController找到上层或者上上层的任意presentingViewController

/**
 从控制器展示的方法presentViewController，解决
 
 方法二，使UIDocumentMenuViewController找不到presentingViewController  
 
 */
- (UIViewController *)presentingViewController {
    
    // Avoiding iOS bug. UIWebView with file input doesn't work in modal view controller
    
    if (_flagged) {
        return nil;
    } else {
        return [super presentingViewController];
    }
}

- (void)presentViewController:(UIViewController *)viewControllerToPresent animated:(BOOL)flag completion:(void (^)(void))completion {
    
    // Avoiding iOS bug. UIWebView with file input doesn't work in modal view controller
    
    if ([viewControllerToPresent isKindOfClass:[UIDocumentMenuViewController class]]
        ||[viewControllerToPresent isKindOfClass:[UIImagePickerController class]]) {
        _flagged = YES;
    }
    
    [super presentViewController:viewControllerToPresent animated:flag completion:completion];
}

2.3 demo 用法：

• 修改测试地址为你自己的URL

NSString *const PRODUCTIONBaseURL = @"https://kunnan.blog.csdn.net/article/details/103902362";

• 从CSDN下载demo https://download.csdn.net/download/u011018979/15133282

https://github.com/zhangkn/KNUIWebViewWithFileInput.git