Load UIImage from URL in iOS

问题

I am trying to load a UIImage from its URL with completionand placeholder image , but neither the UIImage nor the placeholder UIImage are loaded.

Here is my code:

  NSURL *url = [NSURL URLWithString:@"http://assets.gearlive.com/tvenvy/blogimages/stewiegriffin.jpg"];
  NSURLRequest *request = [NSURLRequest requestWithURL:url];

  [self.imageView setImageWithURLRequest:request placeholderImage:[UIImage imageNamed:@"bg.png"]

      success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
          imageView.image = image;
      } 
      failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {}
   ];

回答1:

Use AFnetworking where you can set placeholder image also if the url is not correct. This is more efficient when you are loading images in a tableview or a collection view.

Import UIImageView+AFNetworking.h

#import "UIImageView+AFNetworking.h"

and us the following code:

NSString *url1=@"http://www.fnordware.com/superpng/pnggrad16rgb.png";
[self.image setImageWithURL:[NSURL URLWithString:url1] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

You can download it from gitHub

回答2:

Try this code to get image...

Code:

NSURL *url = [NSURL URLWithString:@"http://www.fnordware.com/superpng/pnggrad16rgb.png"];

NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *image = [UIImage imageWithData:data];

[self.imageview1 setImage:image];

Note: i have used test url. you can use your url.

Update : Swift 3.0 Code :

let url = URL(string: "http://www.fnordware.com/superpng/pnggrad16rgb.png")
    do {
        let  data = try Data(contentsOf: url!)
        var image = UIImage(data: data)
        self.imageView.image = image
        print(image)
    } catch {

    }

Note : In Xcode version 7.1 and above you need to set ATS (App Transport Security). To set ATS you need write below code in info.plist file. Make sure url of image should not be nil.

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

回答3:

Check out AsyncImageView. Its the best async image loader AFAIK. all you have to do is set the image URL to the imageview and the rest is taken care of. including caching.