iphone - 如何在 UIWebView 加载时实现 UIActivityIndi​​catorView？ (iPhone 对象)

Question

我想知道如何在基于 WebView 的应用程序中实现 activityIndi​​cator，我编写了以下代码，但该指示器没有出现。

webview 在本地加载文件，所以加载速度非常快，但是当它加载外部页面时加载速度很慢，我需要指示器...

FirstViewController.h

 #import <UIKit/UIKit.h>

 @interface FirstViewController : 
 UIViewController <UIWebViewDelegate>{
    IBOutlet UIWebView *webview1;   
    NSURL *urlLocation;     
    IBOutlet UIActivityIndicatorView *m_activity; 
 }

 @property (nonatomic, retain) UIActivityIndicatorView *m_activity;

 - (IBAction)searchbutton:(id)sender;
 - (IBAction)home:(id)sender;

 @end

FirstViewController.m

 #import "FirstViewController.h"

 @implementation FirstViewController


 @synthesize m_activity;

 // viewWillAppear loads every time younopen up this View

 - (void)viewWillAppear:(BOOL)animated {
   NSString *filePath = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];          
   urlLocation = [NSURL fileURLWithPath:filePath];  
   [webview1 loadRequest:[NSURLRequest requestWithURL:urlLocation]]; 
 }




 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {     
  if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {      
     //Initialization code      
     m_activity = nil;  
   }    
   return self; 
 }

 - (void)webViewDidFinishLoad:(UIWebView *)webView {    
   m_activity.hidden= TRUE;     
   [m_activity stopAnimating];  
   NSLog(@"Web View started loading...");
 }

 - (void)webViewDidStartLoad:(UIWebView *)webView {     
   m_activity.hidden= FALSE;    
   [m_activity startAnimating];     
   NSLog(@"Web View Did finish loading");
 }

Answer 1

为什么要在 init 中将事件指示器设置为 nil？

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {     
  if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {      
     //Initialization code      
     m_activity = nil;  
   }    
   return self; 
}

对 super 的调用从您的 XIB 初始化了您的指示器(假设您将它连接到 IB 中的 socket )，但是在它被初始化之后您将引用设置为 nil。删除该行。然后返回界面生成器并设置“停止时隐藏”复选框。现在您可以简化显示指标的代码:

- (void)webViewDidFinishLoad:(UIWebView *)webView {
   [m_activity stopAnimating];  
}

- (void)webViewDidStartLoad:(UIWebView *)webView {     
   [m_activity startAnimating];     
}

“停止时隐藏”会导致指示器在您停止动画时隐藏。