Notify with photo attachment

Overview

ZPNs supports sending offline push notifications with a photo attachment.

How it works

ZPNs supports including the "mutable-content":1 field when sending APNs push notifications. This allows your app to intercept the push message, modify its content, and then display it. For more details, please refer to Description of Mutable-content in the Official Documentation of Apple Developer.

Prerequisites

Offline push notifications have been implemented. For details, please refer to Implement offline push notification.
iOS devices with iOS 11.0 or later.

Android device or emulator with Android 9.0 or above version (real device is recommended).

Configure resourceID

Contact ZEGOCLOUD technical support to configure the resourceID with "mutable-content":1.

Sender

ZPNs supports two ways to send a photo attachment, the SDK way and the server API way. The difference between them is that the SDK way can be used for all interfaces that use ZIMPushConfig and only supports iOS devices, while the server API is only applicable to messages pushed to all users on iOS and Google FCM devices.

Sending through the SDK

Configure resourceID

Contact ZEGOCLOUD technical support to configure the resourceID with "mutable-content":1.

When sending offline push notifications with ZIMPushConfig, fill in the above resourceID.

Take sending a text message in a one-to-one chat as an example:

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ZIMPushConfig pushConfig = ZIMPushConfig();
pushConfig.title = "Push title, usually the user's userName, corresponding to APNs title";
pushConfig.content = "Push content, usually the same as the message content, corresponding to APNs body";
pushConfig.resourcesID = "resourceID carrying mutable-content";
pushConfig.payload = "{\"image_attachment\":\"URL of the image resource\"}";

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Sending through a Server API

Please refer to the relevant API documentation Push message to all users for details.

Receiver

Note

Only iOS devices requires corresponding processing on the receiving end to achieve receiving notifications with image attachments. There is no need for processing on the Android devices.

Configure Capability

Open Xcode, select the target under TARGETS, and navigate to Signing & Capabilities > Capabilities. Enable Push Notification (for offline push notifications).

Set up Notification Service Extension

Add a Notification Service Extension to the Targets

Click "File > New > Target..."
In the pop-up window, select "iOS > Notification Service Extension".
Enter the Product Name and other information for the extension.

After creating the extension, a "xxxExtension" folder (xxx is the Product Name entered when adding the extension) will be generated in the project. You will need the NotificationService class file in it.

Configure the Capability for the newly added extension

Select the extension target under TARGETS, and then select "Signing & Capabilities > Capabilities > Push Notification" to enable offline push notifications.

Adjust the minimum supported version of the newly added extension to iOS 11.0 or later

If the iOS version of the device is lower than the requirement here, the extension will not take effect on this device.

Write the logic to add your photo attachment

In the NotificationService.m file in the "xxxExtension" folder (xxx is the Product Name entered when adding the extension), write the logic to add the photo attachment. The sample code is as follows:

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//  NotificationService.m
//  NotificationService

#import "NotificationService.h"
#import <Intents/Intents.h>

@interface NotificationService ()

@property (nonatomic, strong) void (^contentHandler)(UNNotificationContent *contentToDeliver);
@property (nonatomic, strong) UNMutableNotificationContent *bestAttemptContent;

@end

@implementation NotificationService


// When push interception is enabled, this method will be triggered when a push notification with "mutable-content":1 is received.
- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
    self.contentHandler = contentHandler;
    self.bestAttemptContent = [request.content mutableCopy];
    // Title
    NSString *title = self.bestAttemptContent.title;
    // Subtitle
    NSString *subtitle = self.bestAttemptContent.subtitle;
    // Body
    NSString *body = self.bestAttemptContent.body;

    // Extract the payload string carried by the push message
    NSString *payload = [self.bestAttemptContent.userInfo objectForKey:@"payload"];

    if(payload == nil){
        self.contentHandler(self.bestAttemptContent);
        return;
    }
    
    
    // Parse the JSON string and convert it to an NSDictionary
    NSData *jsonData = [payload dataUsingEncoding:NSUTF8StringEncoding];
    NSError *error = nil;
    NSDictionary *payload_json_map = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:&error];
    if (error) {
        self.contentHandler(self.bestAttemptContent);
        return;
    }
    
    
    NSString *imageAttachmentUrl = [payload_json_map objectForKey:@"image_attachment"];
    if(imageAttachmentUrl == nil){
        self.contentHandler(self.bestAttemptContent);
        return;
    }
    
    [self downloadWithURLString:imageAttachmentUrl completionHandle:^(NSData *data, NSURL *localURL) {
        if(localURL){
            UNNotificationAttachment * attachment = [UNNotificationAttachment attachmentWithIdentifier:@"myAttachment" URL:localURL options:nil error:nil];
            self.bestAttemptContent.attachments = @[attachment];
        }
        contentHandler(self.bestAttemptContent);
    }];
    
}

// Method to download and save the image
- (void)downloadWithURLString:(NSString *)urlStr completionHandle:(void(^)(NSData *data,NSURL *localURL))completionHandler{
    __block NSData *data = nil;
    NSURL *imageURL = [NSURL URLWithString:urlStr];
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
    [[session downloadTaskWithURL:imageURL completionHandler:^(NSURL *temporaryFileLocation, NSURLResponse *response, NSError *error) {
        NSURL *localURL;
        if (error != nil) {
            NSLog(@"%@", error.localizedDescription);
        } else {
            NSFileManager *fileManager = [NSFileManager defaultManager];
            localURL = [NSURL fileURLWithPath:[temporaryFileLocation.path stringByAppendingString:@".png"]];
            [fileManager moveItemAtURL:temporaryFileLocation toURL:localURL error:&error];

            NSLog(@"localURL = %@", localURL);
            data = [[NSData alloc] initWithContentsOfURL:localURL];
        }
        completionHandler(data,localURL);

    }]resume];
}

@end

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