Question

您好我从网址获取图片时遇到问题。我从网络服务获取这些网址，然后逐个加载图片，每个网址都附有图片。

-(void)downloadMyfriendReqImage:(NSIndexPath *)path
{
    if (path.row<[arrayPendingRequests count]) {
        NSString *str=[[arrayPendingRequests objectAtIndex:path.row]valueForKey:@"USERIMAGE"];
        UIImage *img = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:str]]];

        if (img==nil) {
            img=[UIImage imageNamed:@"placeholder.png"];
        }

        [dicPendingReqImages setObject:img forKey:str];
        [tblFriendRequests performSelectorOnMainThread:@selector(reloadData) withObject:@"TAG_29" waitUntilDone:NO];
    }
}

这是我用来加载图片的方式。但问题是有些图像没有得到。 img变为空值。但我在android中有相同的应用程序。它完美地加载了所有这些图像。有什么问题..任何人都可以帮助我。

Answer 1

在将NSData请求转换为图像之前检查NSData请求的结果。可能是你从服务器收到超时。

Answer 2

-(void)downloadMyfriendReqImage:(NSIndexPath *)path
{
    if (path.row<[arrayPendingRequests count]) {
        NSString *str=[[arrayPendingRequests objectAtIndex:path.row]valueForKey:@"USERIMAGE"];
        //ADDED LINE
        str=[str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

        UIImage *img = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:str]]];

        if (img==nil) {
            img=[UIImage imageNamed:@"placeholder.png"];
        }

        [dicPendingReqImages setObject:img forKey:str];
        [tblFriendRequests performSelectorOnMainThread:@selector(reloadData) withObject:@"TAG_29" waitUntilDone:NO];
    }
}

我认为你的网址包含一些像NSURL无法读取的空格这样的字符，为了使它能够为字符串添加编码，我认为它应该以这种方式工作..检查代码{{1 }}

Answer 3

试试这个：

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSString *str=[[arrayPendingRequests objectAtIndex:path.row]valueForKey:@"USERIMAGE"];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:str]];
NSURLResponse *response;
NSError *error;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
if (error) {
    // handle error
    return;
}
dispatch_async(dispatch_get_main_queue(), ^{
    // do something with the data
 UIImage *img = [[UIImage alloc] initWithData:data];
});
});

从url获取图像为空值

3 个答案: