如何在后台下载图像以在iOS中设置imageView？

我使用了下面的代码，但不适用于我

UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(markerView.bounds.size.width/10, markerView.bounds.size.height/4, markerView.bounds.size.width*4/5, markerView.bounds.size.height/1.5)];

NSString *strPath = [NSString stringWithFormat:@"%@",[[arrTemp valueForKey:@"image"] objectAtIndex:marker.accessibilityLabel.integerValue]];
NSLog(@"img path %@", strPath);

dispatch_async(dispatch_get_main_queue(), ^{
  UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:strPath]]];
  imgView.image = img;
});

        NSString *str = [NSString stringWithFormat:@"%@",[[[dictTemp valueForKey:@"image"] objectAtIndex:j] valueForKey:@"imagepath"]];
        NSString *strSub = [str stringByReplacingOccurrencesOfString:@" " withString:@"%20"];
        NSURL *imgUrl = [NSURL URLWithString:[NSString stringWithFormat:@"%@",strSub]];

        dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
        dispatch_async(q, ^{
            /* Fetch the image from the server... */
            NSData *data = [NSData dataWithContentsOfURL:imgUrl];
            UIImage *img = [[UIImage alloc] initWithData:data];

            dispatch_async(dispatch_get_main_queue(), ^{

                [imageView setImage:img];
            });
        });

您可以尝试下面的代码。 这对我有用

UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(markerView.bounds.size.width/10, markerView.bounds.size.height/4, markerView.bounds.size.width*4/5, markerView.bounds.size.height/1.5)];

NSString *strPath = [NSString stringWithFormat:@"%@",[[arrTemp valueForKey:@"image"] objectAtIndex:marker.accessibilityLabel.integerValue]];
NSLog(@"img path %@", strPath);

dispatch_async(dispatch_get_main_queue(), ^{
  UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:strPath]]];
  imgView.image = img;
});

        NSString *str = [NSString stringWithFormat:@"%@",[[[dictTemp valueForKey:@"image"] objectAtIndex:j] valueForKey:@"imagepath"]];
        NSString *strSub = [str stringByReplacingOccurrencesOfString:@" " withString:@"%20"];
        NSURL *imgUrl = [NSURL URLWithString:[NSString stringWithFormat:@"%@",strSub]];

        dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
        dispatch_async(q, ^{
            /* Fetch the image from the server... */
            NSData *data = [NSData dataWithContentsOfURL:imgUrl];
            UIImage *img = [[UIImage alloc] initWithData:data];

            dispatch_async(dispatch_get_main_queue(), ^{

                [imageView setImage:img];
            });
        });

您可以尝试下面的代码。 这对我有用

UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(markerView.bounds.size.width/10, markerView.bounds.size.height/4, markerView.bounds.size.width*4/5, markerView.bounds.size.height/1.5)];

NSString *strPath = [NSString stringWithFormat:@"%@",[[arrTemp valueForKey:@"image"] objectAtIndex:marker.accessibilityLabel.integerValue]];
NSLog(@"img path %@", strPath);

dispatch_async(dispatch_get_main_queue(), ^{
  UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:strPath]]];
  imgView.image = img;
});

        NSString *str = [NSString stringWithFormat:@"%@",[[[dictTemp valueForKey:@"image"] objectAtIndex:j] valueForKey:@"imagepath"]];
        NSString *strSub = [str stringByReplacingOccurrencesOfString:@" " withString:@"%20"];
        NSURL *imgUrl = [NSURL URLWithString:[NSString stringWithFormat:@"%@",strSub]];

        dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
        dispatch_async(q, ^{
            /* Fetch the image from the server... */
            NSData *data = [NSData dataWithContentsOfURL:imgUrl];
            UIImage *img = [[UIImage alloc] initWithData:data];

            dispatch_async(dispatch_get_main_queue(), ^{

                [imageView setImage:img];
            });
        });

---

在项目中添加

SDWebImage

文件夹，然后选择以下选项。将文件夹副本添加到目标项目并创建组

然后像这样调用header

#import "UIImageView+WebCache.h"

并确保添加到要使用该库的所有目标

文件位于：

将SDWebImage项目添加到项目中

• 从下载页面下载并解压缩框架的最新版本
• 右键单击项目导航器并选择“将文件添加到您的项目”：
• 在对话框中，选择SDWebImage.framework：
• 选中“将项目复制到目标组的文件夹（如果需要）”复选框

或者你也可以按照其他答案的建议使用

可可豆

终于打电话来了

[imgView sd_setImageWithURL:[NSURL URLWithString:strPath] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

在项目中添加
SDWebImage
文件夹，然后选择以下选项。将文件夹副本添加到目标项目并创建组

然后像这样调用header

#import "UIImageView+WebCache.h"

并确保添加到要使用该库的所有目标


文件位于：

将SDWebImage项目添加到项目中


从下载页面下载并解压缩框架的最新版本
右键单击项目导航器并选择“将文件添加到您的项目”：
在对话框中，选择SDWebImage.framework：
选中“将项目复制到目标组的文件夹（如果需要）”复选框

或者你也可以按照其他答案的建议使用
可可豆

终于打电话来了

[imgView sd_setImageWithURL:[NSURL URLWithString:strPath] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

您可以尝试DispatchQueue.async（xcode 8.0+）：

或者将第一个
DispatchQueue
替换为
URLSession.dataTask

let imageURL: URL = URL(string: "https://www.brightedge.com/blog/wp-content/uploads/2014/08/Google-Secure-Search_SEL.jpg")!

(URLSession(configuration: URLSessionConfiguration.default)).dataTask(with: imageURL, completionHandler: { (imageData, response, error) in

    if let data = imageData {
        DispatchQueue.main.async {
            self.imageView.image = UIImage(data: data)
        }
    }
}).resume()

您可以尝试DispatchQueue.async（xcode 8.0+）：

或者将第一个
DispatchQueue
替换为
URLSession.dataTask

let imageURL: URL = URL(string: "https://www.brightedge.com/blog/wp-content/uploads/2014/08/Google-Secure-Search_SEL.jpg")!

(URLSession(configuration: URLSessionConfiguration.default)).dataTask(with: imageURL, completionHandler: { (imageData, response, error) in

    if let data = imageData {
        DispatchQueue.main.async {
            self.imageView.image = UIImage(data: data)
        }
    }
}).resume()