PINRemoteImage

Fast, non-deadlocking parallel image downloader and cache for iOS

PINRemoteImageManager is an image downloading, processing and caching manager. It uses the concept of download and processing tasks to ensure that even if multiple calls to download or process an image are made, it only occurs one time (unless an item is no longer in the cache). PINRemoteImageManager is backed by GCD and safe to access from multiple threads simultaneously. It ensures that images are decoded off the main thread so that animation performance isn’t affected. None of its exposed methods allow for synchronous access. However, it is optimized to call completions on the calling thread if an item is in its memory cache.

PINRemoteImage supports downloading many types of files. It, of course, supports both PNGs and JPGs. It also supports decoding WebP images if Google’s library is available. It even supports GIFs and Animated WebP via PINAnimatedImageView.

PINRemoteImage also has two methods to improve the experience of downloading images on slow network connections. The first is support for progressive JPGs. This isn’t any old support for progressive JPGs though: PINRemoteImage adds an attractive blur to progressive scans before returning them.

PINRemoteImageCategoryManager defines a protocol which UIView subclasses can implement and provide easy access to
PINRemoteImageManager’s methods. There are built-in categories on UIImageView, PINAnimatedImageView and UIButton, and it’s very easy to implement a new category. See [UIImageView+PINRemoteImage](/Pod/Classes/Image Categories/UIImageView+PINRemoteImage.h) of the existing categories for reference.

Download an image and set it on an image view:

Objective-C

UIImageView *imageView = [[UIImageView alloc] init];
[imageView pin_setImageFromURL:[NSURL URLWithString:@"http://pinterest.com/kitten.jpg"]];

Swift

let imageView = UIImageView()
imageView.pin_setImage(from: URL(string: "https://pinterest.com/kitten.jpg")!)

Download a progressive jpeg and get attractive blurred updates:

Objective-C

UIImageView *imageView = [[UIImageView alloc] init];
[imageView setPin_updateWithProgress:YES];
[imageView pin_setImageFromURL:[NSURL URLWithString:@"http://pinterest.com/progressiveKitten.jpg"]];

Swift

let imageView = UIImageView()
imageView.pin_updateWithProgress = true
imageView.pin_setImage(from: URL(string: "https://pinterest.com/progressiveKitten.jpg")!)

Download a WebP file

Objective-C

UIImageView *imageView = [[UIImageView alloc] init];
[imageView pin_setImageFromURL:[NSURL URLWithString:@"http://pinterest.com/googleKitten.webp"]];

Swift

let imageView = UIImageView()
imageView.pin_setImage(from: URL(string: "https://pinterest.com/googleKitten.webp")!)

Download a GIF and display with PINAnimatedImageView

Objective-C

PINAnimatedImageView *animatedImageView = [[PINAnimatedImageView alloc] init];
[animatedImageView pin_setImageFromURL:[NSURL URLWithString:@"http://pinterest.com/flyingKitten.gif"]];

Swift

let animatedImageView = PINAnimatedImageView()
animatedImageView.pin_setImage(from: URL(string: "http://pinterest.com/flyingKitten.gif")!)

Download and process an image

Objective-C

UIImageView *imageView = [[UIImageView alloc] init];
[self.imageView pin_setImageFromURL:[NSURL URLWithString:@"https://i.pinimg.com/736x/5b/c6/c5/5bc6c5387ff6f104fd642f2b375efba3.jpg"] processorKey:@"rounded" processor:^UIImage *(PINRemoteImageManagerResult *result, NSUInteger *cost)
 {
     CGSize targetSize = CGSizeMake(200, 300);
     CGRect imageRect = CGRectMake(0, 0, targetSize.width, targetSize.height);
     UIGraphicsBeginImageContext(imageRect.size);
     UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRoundedRect:imageRect cornerRadius:7.0];
     [bezierPath addClip];

     CGFloat sizeMultiplier = MAX(targetSize.width / result.image.size.width, targetSize.height / result.image.size.height);

     CGRect drawRect = CGRectMake(0, 0, result.image.size.width * sizeMultiplier, result.image.size.height * sizeMultiplier);
     if (CGRectGetMaxX(drawRect) > CGRectGetMaxX(imageRect)) {
         drawRect.origin.x -= (CGRectGetMaxX(drawRect) - CGRectGetMaxX(imageRect)) / 2.0;
     }
     if (CGRectGetMaxY(drawRect) > CGRectGetMaxY(imageRect)) {
         drawRect.origin.y -= (CGRectGetMaxY(drawRect) - CGRectGetMaxY(imageRect)) / 2.0;
     }

     [result.image drawInRect:drawRect];

     UIImage *processedImage = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
     return processedImage;
 }];

Swift

let imageView = FLAnimatedImageView()
imageView.pin_setImage(from: URL(string: "https://i.pinimg.com/736x/5b/c6/c5/5bc6c5387ff6f104fd642f2b375efba3.jpg")!, processorKey: "rounded")  { (result, unsafePointer) -> UIImage? in

    guard let image = result.image else { return nil }

    let radius : CGFloat = 7.0
    let targetSize = CGSize(width: 200, height: 300)
    let imageRect = CGRect(x: 0, y: 0, width: targetSize.width, height: targetSize.height)

    UIGraphicsBeginImageContext(imageRect.size)

    let bezierPath = UIBezierPath(roundedRect: imageRect, cornerRadius: radius)
    bezierPath.addClip()

    let widthMultiplier : CGFloat = targetSize.width / image.size.width
    let heightMultiplier : CGFloat = targetSize.height / image.size.height
    let sizeMultiplier = max(widthMultiplier, heightMultiplier)

    var drawRect = CGRect(x: 0, y: 0, width: image.size.width * sizeMultiplier, height: image.size.height * sizeMultiplier)
    if (drawRect.maxX > imageRect.maxX) {
        drawRect.origin.x -= (drawRect.maxX - imageRect.maxX) / 2
    }
    if (drawRect.maxY > imageRect.maxY) {
        drawRect.origin.y -= (drawRect.maxY - imageRect.maxY) / 2
    }

    image.draw(in: drawRect)

    UIColor.red.setStroke()
    bezierPath.lineWidth = 5.0
    bezierPath.stroke()

    let ctx = UIGraphicsGetCurrentContext()
    ctx?.setBlendMode(CGBlendMode.overlay)
    ctx?.setAlpha(0.5)

    let logo = UIImage(named: "white-pinterest-logo")
    ctx?.scaleBy(x: 1.0, y: -1.0)
    ctx?.translateBy(x: 0.0, y: -drawRect.size.height)

    if let coreGraphicsImage = logo?.cgImage {
        ctx?.draw(coreGraphicsImage, in: CGRect(x: 90, y: 10, width: logo!.size.width, height: logo!.size.height))
    }

    let processedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return processedImage

}

Handle Authentication

Objective-C

[[PINRemoteImageManager sharedImageManager] setAuthenticationChallenge:^(NSURLSessionTask *task, NSURLAuthenticationChallenge *challenge, PINRemoteImageManagerAuthenticationChallengeCompletionHandler aCompletion) {
aCompletion(NSURLSessionAuthChallengePerformDefaultHandling, nil)];

Swift

PINRemoteImageManager.shared().setAuthenticationChallenge { (task, challenge, completion) in
  completion?(.performDefaultHandling, nil)
}

Support for high resolution images

Currently there are two ways PINRemoteImage is supporting high resolution images:

1. If the URL contains an _2x. or an _3x. postfix it will be automatically handled by PINRemoteImage and the resulting image will be returned at the right scale.
2. If it’s not possible to provide an URL with an _2x. or _3x. postfix, you can also handle it with a completion handler:

NSURL *url = ...;
__weak UIImageView *weakImageView = self.imageView;
[self.imageView pin_setImageFromURL:url completion:^(PINRemoteImageManagerResult * _Nonnull result) {
  CGFloat scale = UIScreen.mainScreen.scale;
  if (scale > 1.0) {
    UIImage *image = result.image;
    weakImageView.image = [UIImage imageWithCGImage:image.CGImage scale:scale orientation:image.imageOrientation];
    }
}];

Set some limits

// cache is an instance of PINCache as long as you haven't overridden defaultImageCache
PINCache *cache = (PINCache *)[[PINRemoteImageManager sharedImageManager] cache];
// Max memory cost is based on number of pixels, we estimate the size of one hundred 600x600 images as our max memory image cache.
[[cache memoryCache] setCostLimit:600 * [[UIScreen mainScreen] scale] * 600 * [[UIScreen mainScreen] scale] * 100];

// ~50 MB
[[cache diskCache] setByteLimit:50 * 1024 * 1024];
// 30 days
[[cache diskCache] setAgeLimit:60 * 60 * 24 * 30];

Installation

CocoaPods

Add PINRemoteImage to your Podfile and run pod install.

If you’d like to use WebP images, add PINRemoteImage/WebP to your Podfile and run pod install.

Carthage

Add github "pinterest/PINRemoteImage" to your Cartfile . See Carthage’s readme for more information on integrating Carthage-built frameworks into your project.

Manually

Download the latest tag and drag the Pod/Classes folder into your Xcode project. You must also manually link against PINCache.

Install the docs by double clicking the .docset file under docs/, or view them online at cocoadocs.org

Git Submodule

You can set up PINRemoteImage as a submodule of your repo instead of cloning and copying all the files into your repo. Add the submodule using the commands below and then follow the manual instructions above.

git submodule add https://github.com/pinterest/PINRemoteImage.git
git submodule update --init

Requirements

PINRemoteImage requires iOS 12.0 or greater.

Contact

Garrett Moon
@garrettmoon
Pinterest

License

Copyright 2015 Pinterest, Inc.

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.