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Category: iOS

Programmatically selecting a row in a UITableView

I had a need to programmatically select a row in a UITableView. In order to do this, you have to do two things:

 
let indexPath = IndexPath(row: 0, section: 0)
self.tableView.selectRow(at: indexPath, animated: true, scrollPosition: .none)
self.tableView.delegate?.tableView!(self.tableView, didSelectRowAt: indexPath)

selectRow highlights the selected row and didSelectRowAt will call didSelectRowAt if you need to perform whatever action you defined.

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Fastlane solution for Crashlytics – Missing dSYMs

While working on a new Xcode project, I was unable to get my crash logs on Crashlytics . In the Crashlytics dashboard, I would see the following error:

"Found 1 unsymbolicated crash from missing dSYMs in 1 version in the last 24 hours"

Crashlytics even had a page dedicated to this: All about Missing dSYMs.

In my case the issue was with bitcode being enabled, which it is by default on all new iOS Projects. When bitcode is enabled, Apple recompiles your project on their server. Then you need to download the dSYMS to your computer and upload them to Crashlytics. This is a manual process that takes a lot of time. I was dreading doing this a second time after figuring out the process.

I figured this is something that fastlane might be able to help me with. Sure enough, they’ve come up with a lane to automate this. You can read more about it here:

Automatically download and upload dSYM symbolication files from iTunes Connect for Bitcode iOS apps using fastlane

Simply add this to your Fastfile:

lane :refresh_dsyms do
  download_dsyms                  # Download dSYM files from iTC
  upload_symbols_to_crashlytics   # Upload them to Crashlytics
  clean_build_artifacts           # Delete the local dSYM files
end

Then run it like this:

fastlane refresh_dsyms

Thanks fastlane!

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DispatchGroup with Swift

Sometimes you have a need to wait on several asynchronous tasks before doing something in your code. DispatchGroup is a powerful API that lets you group together these tasks into one task.

DispatchGroup allows for aggregate synchronization of work. You can use them to submit multiple different work items and track when they all complete, even though they might run on different queues. This behavior can be helpful when progress can’t be made until all of the specified tasks are complete.

For example you have a ViewController that shows data from three different APIs. You need data from all 3 API’s before you can render the page. One way to do this would be to chain network calls and render the page after the 3rd API completed. But this leads to ugly nest code and requires that the APIs be called synchronously, rather than asynchronously.

Let’s looks look at how to solve this problem by chaining first.

I’ll be using httpbin.org for these examples. It’s a great tool for testing HTTP requests and responses.

This URL allows you to make an HTTP request that will wait a duration in seconds. For example, this will take 10 seconds to load:
https://httpbin.org/range/1024?duration=10

I’m using this API so you can easily see the time difference.

I wrote a simple method called makeNetworkRequest(), which take a duration in seconds and uses NSURLSession to call httpbin.org:

    func makeNetworkRequest(duration:Int, completion: @escaping (_ result: String?) -> Void) {
        let config = URLSessionConfiguration.default
        let session = URLSession(configuration: config)
        let url = URL(string: "https://httpbin.org/range/1024?duration=\(Int(duration))")!
        NSLog("makeNetworkRequest() \(url)")
        let task = session.dataTask(with: url) { (data, response, error) in
            if error != nil {
                NSLog(error!.localizedDescription)
                completion(nil)
            } else {
                if let str = String(data: data!, encoding: String.Encoding.utf8) {
                    completion(str)
                } else {
                    completion(nil)
                }

            }
        }
        task.resume()
    }

 

Here is an example using nesting:

makeNetworkRequest(duration: 2) { (str) in
	NSLog("Request #1 \(str ?? "nil"))\n")

	makeNetworkRequest(duration: 3) { (str) in
		NSLog("Request #2 \(str ?? "nil"))\n")

		makeNetworkRequest(duration: 10) { (str) in
			NSLog("Request #3 \(str ?? "nil"))\n")
			
			NSLog("Done!")
		}
	}
}

As you can see this accomplishes a solution to our problem, but there is a lot of nested code and called the API’s synchronously. It took 15 seconds to wait for all 3 responses.

Now let’s try this with DispatchGroup. With DistpatchGroup you first create a DistpachGroup:

let group = DispatchGroup()

For each block of code you want to execute you call:

group.enter()

Before the API and then

Group.leave()

When it finishes executing.

Finially group.notifiy(…) will be called when all group.enter() calls have a successful group.leave() response:

group.notify(queue: DispatchQueue.global(qos: .background)) {
NSLog(“All 3 network reqeusts completed”)
completion(strings)
}

Here’s a complete example:

func makeNetworkRequests(completion: @escaping (_ result: String?) -> Void) {
        let group = DispatchGroup()
        var strings = "start"
        
        group.enter()
        makeNetworkRequest(duration: 2) { (str) in
            NSLog("Request #1 \(str ?? "nil"))\n")
            if let str = str {
                strings = strings + str
            }
            group.leave()
        }
        
        group.enter()
        makeNetworkRequest(duration: 3) { (str) in
            NSLog("Request #2 \(str ?? "nil"))\n")
            if let str = str {
                strings = strings + str
            }
            group.leave()
        }
        
        group.enter()
        makeNetworkRequest(duration: 10) { (str) in
            NSLog("Request #3 \(str ?? "nil"))\n")
            if let str = str {
                strings = strings + str
            }
            group.leave()
        }
        
        group.notify(queue: DispatchQueue.global(qos: .background)) {
            NSLog("All 3 network reqeusts completed")
            completion(strings)
        }
    }

Notice how much easier this code is to read. No more nested blocks. It’s also asynchronous. It only takes 10 seconds for all 3 to return, because we’re only waiting on the longest API to respond.

You can find a sample application using this API here:

https://github.com/dougdiego/DispatchGroupDemo

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PHImageManager requestImageData with Photos iCloud Photo Library

I came across a bug the other day because of photos in the iCloud Photo Library. In my app I was showing a grid of images to be selected. If “iCloud Photo Library” was enabled then user could see the thumbnail and pick the image, but the app failed when it tried to do something with the image. This is because the image wasn’t downloaded yet.

This is what my code looked like.

let manager = PHImageManager.default()
let requestOptions = PHImageRequestOptions()
requestOptions.resizeMode = .exact
requestOptions.deliveryMode = .highQualityFormat;

// Request Image
manager.requestImageData(for: asset, options: requestOptions, resultHandler: { (data, str, orientation, info) -> Void in
	// Do somethign with Image Data
 })

I found the property: PHImageRequestOptions.isNetworkAccessAllowed. When enabled, the image is downloaded from iCloud. And you can set a progressHandler to inform the user.

I updated the code to look like:

let manager = PHImageManager.default()
let requestOptions = PHImageRequestOptions()
requestOptions.resizeMode = .exact
requestOptions.deliveryMode = .highQualityFormat;
requestOptions.isNetworkAccessAllowed = true;
requestOptions.progressHandler = { (progress, error, stop, info) in
    if(progress == 1.0){
        SVProgressHUD.dismiss()
    } else {
        SVProgressHUD.showProgress(Float(progress), status: "Downloading from iCloud")
    }
}

// Request Image
manager.requestImageData(for: asset, options: requestOptions, resultHandler: { (data, str, orientation, info) -> Void in
	// Do somethign with Image Data
 })

The requestImageData API, returns an info dictionary providing information about the status of the request. Documentation on the key is here:
PHImageManager -Image Result Info Keys

PHImageResultIsInCloudKey A Boolean value indicating whether the photo asset data is stored on the local device or must be downloaded from iCloud.

You could also check this key to see if downloading the image is required.

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App Store Review Times – Automation?

Recently Apple shortened their review times from about 7 days to about 1 day.

You can follow the latest review times at appreviewtimes.com
appreviewtimes

How is Apple doing this? It could be new leadership. It could policy changes. It could be more people. While it may be all of these, I think it has something to do Automation.

Each year Apple has been getting better with their testing tools. In iOS 9, they made a big improvement with UI Testing tools. Xcode now allows you to record your UI Tests. Basically click a record button and then navigate your app in the Simulator. It’s a bit more complicated than that, but almost that easy.

What if Apple modified their testing tools, so the App Store Review team could record their review sessions. Once they have a recording for an app, they can run that recording on new submissions. If it passes, they approve the App. If it fails, they give the app a quick look through and fix the UI test.

They could have started recording session months in advance and then all of a sudden turned it on. If an App hadn’t been approved in a while or it was a new app, the first review would take longer. But after that, it would be fast.

I have no idea if this is what they are really doing, just fun speculation. I hope we’ll learn more at WWDC 2016.

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Fastlane Frameit Tips

Here are few tips I learned when setting up Fastlane Frameit.

When I first ran fame it, I got this error:

$ frameit white

iconv: /Users/doug/src/my-ios-project/fastlane/screenshots/en-US/title.strings:1:252: incomplete character or shift sequence
[16:37:51]: Could not get title for screenshot ./iPhone6-0.png. Please provide one in your Framefile.json

iconv: /Users/doug/src/my-ios-project/fastlane/screenshots/en-US/title.strings:1:252: incomplete character or shift sequence
[16:37:52]: Could not get title for screenshot ./iPhone6-1.png. Please provide one in your Framefile.json

iconv: /Users/doug/src/my-ios-project/fastlane/screenshots/en-US/title.strings:1:252: incomplete character or shift sequence
[16:37:53]: Could not get title for screenshot ./iPhone6-2.png. Please provide one in your Framefile.json
ç
iconv: /Users/doug/src/my-ios-project/fastlane/screenshots/en-US/title.strings:1:252: incomplete character or shift sequence
[16:37:55]: Could not get title for screenshot ./iPhone6-3.png. Please provide one in your Framefile.json
√
iconv: /Users/doug/src/my-ios-project/fastlane/screenshots/en-US/title.strings:1:252: incomplete character or shift sequence
[16:37:56]: Could not get title for screenshot ./iPhone6-4.png. Please provide one in your Framefile.json

As the documentation clear states: “.strings files MUST be utf-16 encoded (UTF-16 LE with BOM).”

I fixed this by saving the file ast UTF-16 in TextWrangler.
textwrangler_utf-16

Then I ran into a strange error:

$ frameit white
[16:42:10]: `mogrify -gravity Center -pointsize 55 -draw text 0,0 'Text 1' -fill #000000 /var/folders/rf/yz3fgzq17sbgkjcxfq_x6lh40000gn/T/mini_magick20160324-45310-1yizv31.png` failed with error:
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: non-conforming drawing primitive definition `text' @ error/draw.c/DrawImage/3165.

[16:42:12]: `mogrify -gravity Center -pointsize 55 -draw text 0,0 'Text 2' -fill #000000 /var/folders/rf/yz3fgzq17sbgkjcxfq_x6lh40000gn/T/mini_magick20160324-45310-qp00up.png` failed with error:
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: non-conforming drawing primitive definition `text' @ error/draw.c/DrawImage/3165.

[16:42:13]: `mogrify -gravity Center -pointsize 55 -draw text 0,0 'Text 3' -fill #000000 /var/folders/rf/yz3fgzq17sbgkjcxfq_x6lh40000gn/T/mini_magick20160324-45310-eu9yaq.png` failed with error:
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: non-conforming drawing primitive definition `text' @ error/draw.c/DrawImage/3165.

[16:42:15]: `mogrify -gravity Center -pointsize 55 -draw text 0,0 'Text 4' -fill #000000 /var/folders/rf/yz3fgzq17sbgkjcxfq_x6lh40000gn/T/mini_magick20160324-45310-1ie72eo.png` failed with error:
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: non-conforming drawing primitive definition `text' @ error/draw.c/DrawImage/3165.

[16:42:16]: `mogrify -gravity Center -pointsize 55 -draw text 0,0 'Text 5' -fill #000000 /var/folders/rf/yz3fgzq17sbgkjcxfq_x6lh40000gn/T/mini_magick20160324-45310-ji9gyl.png` failed with error:
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: unable to read font `(null)' @ error/annotate.c/RenderFreetype/1153.
mogrify: non-conforming drawing primitive definition `text' @ error/draw.c/DrawImage/3165.

I came across a forum thread that said I needed to install ghostscript. So I installed Ghostscript with Homebrew like:

$ brew install gs
==> Installing dependencies for ghostscript: libtiff, little-cms2
==> Installing ghostscript dependency: libtiff
==> Downloading https://homebrew.bintray.com/bottles/libtiff-4.0.6.el_capitan.bottle.tar.gz
######################################################################## 100.0%
==> Pouring libtiff-4.0.6.el_capitan.bottle.tar.gz
🍺  /usr/local/Cellar/libtiff/4.0.6: 259 files, 3.4M
==> Installing ghostscript dependency: little-cms2
==> Downloading https://homebrew.bintray.com/bottles/little-cms2-2.7.el_capitan.bottle.tar.gz
######################################################################## 100.0%
==> Pouring little-cms2-2.7.el_capitan.bottle.tar.gz
🍺  /usr/local/Cellar/little-cms2/2.7: 16 files, 1M
==> Installing ghostscript
==> Downloading https://homebrew.bintray.com/bottles/ghostscript-9.18.el_capitan.bottle.tar.gz
######################################################################## 100.0%
==> Pouring ghostscript-9.18.el_capitan.bottle.tar.gz
🍺  /usr/local/Cellar/ghostscript/9.18: 709 files, 61M

Then it ran successfully:

$ frameit white
[16:45:21]: Added frame: '/Users/doug/src/my-ios-project/fastlane/screenshots/en-US/iPhone6-0_framed.png'
[16:45:23]: Added frame: '/Users/doug/src/my-ios-project/fastlane/screenshots/en-US/iPhone6-1_framed.png'
[16:45:25]: Added frame: '/Users/doug/src/my-ios-project/fastlane/screenshots/en-US/iPhone6-2_framed.png'
[16:45:28]: Added frame: '/Users/doug/src/my-ios-project/fastlane/screenshots/en-US/iPhone6-3_framed.png'
[16:45:30]: Added frame: '/Users/doug/src/my-ios-project/fastlane/screenshots/en-US/iPhone6-4_framed.png'
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Managing where rows can be moved to in UITableView

In an app I was working on, I needed to prevent users from moving rows from section 1 to section 0. After reading the docs, I found Apple has just the API: Reordering Table Rows.

Here’s how I used the API. If the proposed destination section is 0, then return the current indexPath. As a result the user will be unable to draw a row from section 1 to section 0.

func tableView(tableView: UITableView, targetIndexPathForMoveFromRowAtIndexPath sourceIndexPath: NSIndexPath, toProposedIndexPath proposedDestinationIndexPath: NSIndexPath) -> NSIndexPath
{
    
    if proposedDestinationIndexPath.section == 0 {
        return sourceIndexPath
    }
    
    return proposedDestinationIndexPath;
}

My problem was simple, but this API could be used for all kinds of reordering problems.

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Xcode 7 crashing when toggling Assistant editor

I had a Xcode project which was crashing whenever I tried to close the Assistant editor.  Here is what I did to fix it.

  1. Close the project in XCode
  2. Delete the following files using the Terminal.  Where “myproject” is the name your project.
rm -rf myproject.xcworkspace/xcuserdata

rm -rf myproject.xcodeproj/xcuserdata

rm -rf myproject.xcodeproj/project.xcworkspace

If you don’t feel comfortable using the Terminal, you can also right click on the file and choose “Show Package Contents” and delete the files.

If you don’t use CocoaPods, you may not have a myproject.xcworkspace

This solution may fix other Xcode crashing issues.

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Migrate NSUserDefaults to App Groups – Swift

I needed migrate my NSUserDefaults to using App Groups. I came across this post Migrating to App Groups, which was doing exactly what I wanted in Objective-C. Here’s the version I rewrote in Swift:

func migrateUserDefaultsToAppGroups() {
	
	// User Defaults - Old
	let userDefaults = NSUserDefaults.standardUserDefaults()
	
	// App Groups Default - New
	let groupDefaults = NSUserDefaults(suiteName: "group.myGroup")
	
	// Key to track if we migrated
	let didMigrateToAppGroups = "DidMigrateToAppGroups"
	
	if let groupDefaults = groupDefaults {
		if !groupDefaults.boolForKey(didMigrateToAppGroups) {
			for key in userDefaults.dictionaryRepresentation().keys {
				groupDefaults.setObject(userDefaults.dictionaryRepresentation()[key], forKey: key)
			}
			groupDefaults.setBool(true, forKey: didMigrateToAppGroups)
			groupDefaults.synchronize()
			print("Successfully migrated defaults")
		} else {
			print("No need to migrate defaults")
		}
	} else {
		print("Unable to create NSUserDefaults with given app group")
	}
	
}

Gist

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Cocoapods – Generated duplicate UUIDs

I recently added another target to my Podfile to support tvOS. Here is an example of what the Podfile looks like:

source 'https://github.com/CocoaPods/Specs.git'
use_frameworks!

target 'AppiOS' do
        platform :ios, '9.0'
        pod 'AFNetworking', '3.0.0-beta.1'
end

target 'AppTV' do
    platform :tvos, '9.0'
    pod 'AFNetworking', '3.0.0-beta.1'
end

I got this really long error complaining of duplicate UUIDS. Here is a shortened version:

[!] [Xcodeproj] Generated duplicate UUIDs:

PBXFileReference -- 
.... /Products/AFNetworking.framework

From what I understand, this deterministic UUIDs is a harmless warning and can be disabled by running the following command in the terminal. Then run pod install again.

$ export COCOAPODS_DISABLE_DETERMINISTIC_UUIDS=YES
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