Question

我有一些问题我想从特定链接下载来自互联网的图像下载此图像发生在其他类中，即singlton类名称moreAppInternet.m

我的moreAppInterNet.m文件如下

// finishedImgDling是bool

// mutableData是NSMutableData

// urlConnection是NSURLConnection

// appimage是UIImage

// imageUrl是包含链接的NSString

+（ID）sharedManager {

static moreAppInterNet *sharedMyManager = nil;

@synchronized(self) {

    if (sharedMyManager == nil)

        sharedMyManager = [[self alloc] init];
}

return sharedMyManager;

}

- （无效）downloadImageFromUrl {
finishedImgDling = NO;

[self.mutableData setLength:0];

self.urlConnection = [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:self.imageUrl]] delegate:self];


while(!finishedImgDling) {
    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}

}

- （void）connection：（NSURLConnection *）connection didReceiveResponse：（NSURLResponse *）response {

if (connection == self.urlConnection)
{

    NSLog(@"imageDling");
}

}

- （void）connection：（NSURLConnection *）connection didReceiveData：（NSData *）data {

if (connection == self.urlConnection)
{

    if (self.mutableData == nil)
    {
        self.mutableData = [NSMutableData data];
    }

    [self.mutableData appendData:data];
}

}

- （void）connectionDidFinishLoading：（NSURLConnection *）连接 {

if (connection == self.urlConnection)
{
    NSLog(@"image Downloaded");

    finishedImgDling = YES;

    [self setUrlConnection:nil];

    [self storeImage];
}

}

- （无效）storeImage {

[self setAppimage:nil];

self.appimage = [UIImage imageWithData:self.mutableData];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];     
NSFileManager *fileManager = [NSFileManager defaultManager];

NSString *path =[documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"appImage.png"]];

[fileManager createFileAtPath:path contents:UIImagePNGRepresentation(self.appimage) attributes:nil];

 NSLog(@"downloading and storing complete");

}

我的另一个ViewController如下所示，我称之为该函数

- （无效）viewDidLoad中 {

[moreAppInterNet sharedManager];

[self downloadImage];

}

- （无效）downloadImage {

 NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(download_Image_from_other_class) object:nil];

NSOperationQueue *que = [[NSOperationQueue alloc] init];

[que addObserver:self forKeyPath:@"operations" options:0 context:NULL];

[que addOperation:operation];

[operation release];

self.dlingQue = que;

[que release];

}

- （无效）download_Image_from_other_class {

[[moreAppInterNet sharedManager] downloadImageFromUrl];

}

- （void）observeValueForKeyPath：（NSString *）keyPath ofObject：（id）object 更改：（NSDictionary *）更改上下文：（void *）上下文 {

if ([keyPath isEqualToString:@"operations"] && object == self.dlingQue)
{

    if ([self.dlingQue operationCount] == 0)
    {

        self.imgView = [[moreAppInterNet sharedManager] appimage];

        //it takes lots of time to display image in UIImageView
        //Even though Above line get executed
    }
}
else {

    [super observeValueForKeyPath:keyPath ofObject:object
                           change:change context:context];
}

}

问题是 self.imgView需要很多时间来加载图像大约5秒，即使它已完全下载

任何人都可以帮助我或告诉我我做错了什么

Answer 1

我用于网络的库是AFNetworking

Answer 2

我认为您的代码会在您请求时再次下载图片。

您需要检查downloadImageFromUrl中是否包含该文件。

可能您需要更强大的库来处理文件下载。

UIImageView需要时间来加载图像

2 个答案: