我想使用ASIHTTPRequest
执行多个下载过程,并使用代码
修改
- (void)download{
UIImageView *image = (UIImageView *)[mainView viewWithTag:selectedTag];
for (UIProgressView *currentProgress in [image subviews]) {
if ([currentProgress isKindOfClass:[UIProgressView class]]) {
if(currentProgress)
{
currentProgress.progress = 0.0;
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:[urlArray objectAtIndex:selectedTag]]];
request.delegate = self;
[request setDownloadProgressDelegate:currentProgress];
[request setShowAccurateProgress:YES];
[request shouldContinueWhenAppEntersBackground];
[request allowResumeForFileDownloads];
[request startAsynchronous];
}
}
}
}
- (void)request:(ASIHTTPRequest *)request didReceiveData:(NSData *)data{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(progressUpdate:)
name:@"ProgressNotification"
object:nil];
}
这工作正常,现在我想继续这个过程,即使我导航到另一个viewcontroller
,也没有暂停或取消当前下载UIProgressView
进度。
请帮忙。
答案 0 :(得分:2)
只要在UIViewController中保存对ASIHTTPRequest的引用,它就可以工作。
其次,您必须确保未释放整个UIViewController,例如从UINavigationControllers弹出非根视图控制器。
此外,在相关说明中,请参阅页面顶部的here,ASIHTTPRequest不再被开发。
修改强>
我用一个带有两个标签的简单应用程序对此进行了测试,其中第一个UIViewController在加载时立即开始下载。由于ASIHTTPRequest在其自己的线程内异步运行,因此它会不断更新进度条,无论它是否在视图中。当我切换到第二个选项卡并在几秒钟后返回时,进度条已经提前。
// FirstViewController.h
#import <UIKit/UIKit.h>
#import "ASIHTTPRequest.h"
@interface FirstViewController : UIViewController {
IBOutlet UIProgressView *progressView;
ASIHTTPRequest *request;
}
@property (nonatomic,retain) ASIHTTPRequest *request;
@end
// FirstViewController.m
#import "FirstViewController.h"
@interface FirstViewController ()
@end
@implementation FirstViewController
@synthesize request;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
self.title = NSLocalizedString(@"First", @"First");
self.tabBarItem.image = [UIImage imageNamed:@"first"];
self.request = nil;
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
if (request==nil) {
request=[[ASIHTTPRequest alloc] initWithURL:[NSURL URLWithString:@"http://largefile.zip"]];
[request setDownloadProgressDelegate:progressView];
[request setShowAccurateProgress:YES];
[request shouldContinueWhenAppEntersBackground];
[request allowResumeForFileDownloads];
[request startAsynchronous];
}
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
} else {
return YES;
}
}
- (void) dealloc {
if (request!=nil) {
[request clearDelegatesAndCancel];
[request release];
}
}
@end
如上所述,另一种方法是将下载数据的功能放入单例中。作为ASIHTTPRequest代理的单例将通过实现
通知您的UIViewController有关自定义通知的下载进度- (void)request:(ASIHTTPRequest *)request didReceiveData:(NSData *)data;
并致电
[[NSNotificationCenter defaultCenter] postNotificationName:@"MyCustomNotification" object:self];
同样,由于下载在自己的线程中运行,因此即使UIViewController不在视图中,也会收到通知。 您的UIViewController必须让NSNotificationCenter知道它想要通过调用
来接收通知 [[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(progressUpdate:)
name:@"MyCustomNotification"
object:nil];
作为最后一点,请不要忘记致电
[[NSNotificationCenter defaultCenter] removeObserver:self];
当你解除你的UIViewController时。