I've been developing iOS apps for some time now and I'm aware that the iOS simulators run code faster than their hardware counterparts - i.e. actual devices. I read the following on Apple's Testing and Debugging in Simulator documentation site.
Because the simulator is an app running on a Mac, it has access to the computer’s resources, including the CPU, memory, and network connection. All of these resources are likely to be faster than those found on a mobile device. As a result, the simulator is not an accurate test of an app’s performance, memory usage, and networking speed.
I understand that completely. I also understand that it's important to have multiple simulators to test different size-classes/resolutions.
What I don't understand, however, is why Apple include so many simulators for devices with the same resolution. See the following picture showing iPhone 6, 6s and 7 - all of which have the same screen size and resolution.
Given that the simulator runs at 'full speed' (regardless of which devices its actually simulating), what's the point of having all those simulators (each taking up a few GB of storage)?
Thanks in advance,
Loic
Each device type attempts to simulate the respective physical device, including features like the presence of force touch. If your trackpad supports force touch the Simulator will translate that into force on the simulated device, but only for device types that support it. There are also things like graphics class and memory class that enable or disable certain behaviors. (In theory Jetsam should more aggressively evict background apps on the iPhone 5 simulator compared to the iPad Pro simulator.)
You can use xcrun simctl to create or delete devices, including the default devices though Xcode updates may re-create default devices.
You can also create multiple simulator instances for the same device type if you want different photo libraries, permission settings (grant your app permission to use location in one and deny it in the other), and so forth.
Related
The iOS simulador that installs with Xcode is a VM or a emulator like Android does?
It's neither a Virtual Machine nor an Emulator. It's a simulator, in another words it's a standard mac application which mimic the behaviour of iOS devices. It mimics most of the features of an actual devices, but lacks some major features. So you need to use a real device for testing some of the real world scenarios.
You can read more about simulators here : About Simulator
I would like to quote some key information from the above linked page:
What is Simulator
Simulator allows you to rapidly prototype and test builds of your app
during the development process. Installed as part of the Xcode tools,
Simulator runs on your Mac and behaves like a standard Mac app while
simulating an iPhone, iPad, Apple Watch, or Apple TV environment.
Think of the simulator as a preliminary testing tool to use before
testing your app on an actual device.
Need of actual device for Testing
Simulator is a useful tool, but it should not be the only way you test
an app. Because the simulator is an app running on a Mac, it has
access to the computer’s resources, including the CPU, memory, and
network connection. All of these resources are likely to be faster
than those found on a mobile device. As a result, the simulator is not
an accurate test of an app’s performance, memory usage, and networking
speed. For this same reason, always test the performance of your app’s
user interface on a device. In Simulator, your app’s user interface
may appear to run both faster and smoother than on a device.
Also keep in mind that some user interface elements can be easier to
interact with in Simulator using a mouse than when trying to interact
with the app through touch on a device.
Finally, there are some hardware and API differences in Simulator.
These differences may affect your app when testing in Simulator.
I wanted to know whether the iPhone Simulator in XCode "really" emulates the device hardware.
So when deploying to iPhone 4s Simulator, will my app actually be "as slow as on a real iPhone 4S device" and when using an iPhone 6 Simulator, will it be as fast as on a real device?
The simulator does a really lousy job of indicating app performance. In fact it doesn't try.
For most things the simulator is much, much faster than an iOS device. It runs your code on an x86 processor, which is much faster than the ARM and has many times more memory. (It also actually links again OXS frameworks, not iOS frameworks. There is glue code in the simulator that makes it work with iOS code, but it's not perfect.)
However, some things, like Core Image filters and OpenGL graphics, are actually slower on the simulator than on a real iOS device.
The bottom line is that you can't really tell ANYTHING about your app's performance from the simulator, and shouldn't try. You can do basic development on the sim, but when it comes time to test performance, use real devices, and make sure to test on the oldest/slowest device your app supports (usually an iPhone 4s or iPad 2).
You also can't test memory usage on the simulator. A program that will run out of memory and crash on an iOS device may run just fine on the simulator.
The Simulator is a useful tool, and it should not be the only way you
test an app. Because the Simulator is an app running on a Mac, it has
access to the computer’s resources, including the CPU, memory, and
network connection. All of these resources are likely to be faster
than those found on a mobile device. As a result, the simulator is not
an accurate test of an app’s performance, memory usage, and networking
speed.
Source
I would like to start developing for iOS. Coming from an Android developing background, I know that the more types of devices you can get your hands on, the better testing will be, as all devices have wildly different specs, and what may work perfectly in your test device may not even run in another one, let alone look good.
I know that testing on the actual device is very important, as there are many limitations on what you can test on an emulator, so I've decided to get an actual device.
However, there are also tons of devices available in the iOS world! There's the iPod touch, the iPad and the iPhone, each in several different generations and configurations (8GB version vs 16GB version, WiFi version, 3G version, etc.). Not also the screen sizes, but also the aspect ratio is very different across devices, and also the included sensors.
I think that getting an application to run in varied devices should not be difficult, but is it necessary to actually test on all the device types you plan to support? Apple is not renown for its low price, and I would like to keep the starting costs as low as possible.
So, to conclude: Is it necessary/recommended to test on as many device types as you can in the iOS development world?
A small clarification: I'm specially asking if it is possible for there to be compatibility issues related to a specific device/family-of-devices that I would not be able to catch either by testing on the emulator nor a totally different device.
Generally speaking, the major differences in capabilities between testing on the simulator and testing on a device are:
The simulator does not use exactly the same sandboxing as the device. So, for instance, if your provisioning profile is missing your Passbook credentials, this problem will show up on a physical device but not on the simulator.
The simulator doesn't generally support GPS, multitouch, push notifications, Bluetooth, and some other specific features.
On a non-retina display, the simulator view for an iPhone 5+ or (especially!) a retina iPad will be nigh unusable at 100% because its size will exceed the size of your screen.
There are a few, very rare, crashes that occur only on the simulator and a few that occur only on the device.
The simulator does not always support the earliest iOS versions your app supports. For instance, the current version of Xcode (which you must use if you want to build for the latest iOS version) only has simulators from 5.0+ available.
Certain profiling with Instruments is, as far as I can tell, only available in the Simulator.
Now, in my specific case, I try to test on one of each screen resolution I support and one of each major OS version I support.
This boils down to the following array of test devices:
(480x320) iPhone 3GS running 4.3.3
(1136x640) iPod 5gen running the latest 6.x
(960x640) iPhone 4S running 6.0
(1024x768) iPad 1st gen running 5.0
(2048x1536) iPad 4th gen running the latest 6.x
Note that the iPad mini is the same resolution as the iPad 1st gen.
(My choices are skewed towards later iOS versions since I like to implement integration with all of Apple's snazzy optional features as they roll them out. It would probably be a more balanced assortment if one of the 6.x devices were running 5.1 instead.)
If you don't need to support 4.x, I would personally advise against it, since iTunes Connect no longer collects crash reports for it and the simulator no longer offers it. Of course, only you can decide whether you really need to or not, and if you do, focus a lot of your testing there as Xcode does not warn you if you are using APIs that were only introduced in 5.0, which will crash any device running 4.x.
Please note that there are ways to (with significant preparation) downgrade the version of iOS on a device, so if you really want to test more versions than you have devices for, you can (with a lot of effort). But you're probably better off cultivating a strong pool of beta testers for this, anyway.
Whilst it's obviously great to test on all possible devices, the iOS ecosystem is much tighter than Android, so you can narrow down the field somewhat.
You can start by limiting your target iOS versions. That will anyway cut out a number of older devices. iOS6 share of all iOS devices is now probably around 75% 4 months after release; iOS5+iOS6 upwards of 90%. If you are just now starting to develop for iOS, you could probably just target iOS6.
That means your minimum hardware platform is iPad2 / iphone3GS / ipodTouch4
Total list of devices
iPad: 2 3 4 mini
iPhone: 3GS 4 4S 5
iPod: 4 5
Ten devices.
But you won't need to test them all. You could sensibly narrow it to...
iPad: mini + one of the retina models
iPhone: 3GS + 5
for everyday testing.
Obviously if you do want to be more back-compatible, just replace the lower-end testing model for a lower-spec device (iphone 3, iPad 1).
The difference in storage capacity (8GB vs 16GB for example) will be mostly immaterial.
There are some hardware features you will have to pay special attention to, depending on your project. The obvious one is retina vs non-retina displays. Hardware features for location services is particularly nuanced between models.
Lowendmac have a pretty thorough iphone comparison chart...
I think that getting an application to run in varied devices should
not be difficult, but is it necessary to actually test on all the
device types you plan to support?
That depends a lot of what kind of apps you intend to build. For example, universal apps run on both small- and large-screen devices but may present themselves differently on each, so you'd want to be able to try both. Many apps target iPad specifically, so obviously testing on small devices isn't necessary. iPod Touch and iPhone are very similar, so testing on one or the other is often sufficient.
In short, you don't have to own every version of every device, and you don't probably don't have to test on every single version of iOS that's ever been released. But you do want to get your product tested on as many different devices and operating system versions as you can. So, cultivate a group of beta testers who will help you out by trying your app on their devices. The iOS developer program lets you add up to 100 test devices to your account precisely so that you can get your app tested in lots of different circumstances.
Testing on the iPod touch is generally not worth it.
In the iOS world, there is generally the iPhone/iPod, the iPhone 5/iPod 5th generation, and the iPad.
So, that is a total of 3 screen sizes.
If you plan on targeting more than the latest OS (iOS 6), that is where the complexity of testing comes in. Simply targeting iOS 5, and iOS 6 nearly doubles the amount of targets you need to test for.
I try and keep it simple. I test on my iPhone 5, and my iPad. Both of those run iOS 6. For iOS 5 and the small iPhone, I rely on the simulator.
I develop for both Android and iOS, so I get where this question is coming from. I have the luxury of being able to develop on most of the different iOS devices and I would say that in most cases I would feel comfortable testing on the least advanced device my user will be using. If it runs smooth on a iPOd 3rd gen then it is going to run very smooth on an iPhone 4S, 5, etc. For the different screen height for the iPhone 5, the simulator works very good with laying it out.
Things you will need to consider is if your apps have the option to use certain feature only a phone would have, like making calls. Also if you want to make a iPad or universal app, it would be very handy to have an actual iPad, but the simulator does work very good.
I'm learning iOS development and I need to know what hardware I need to test my apps.
Is the iPhone/iPad simulator in Xcode sufficient? Or do I need the hardware? I have an iPad 2, and an iPhone 3G. The iPad 2 is one generation old, while my iPhone 3G is three generations old.
My first project is a basic card game with networking, based on a tutorial.
Opinion: Considering the number of questions I see of the form "this works great on the simulator but not on my device" I'd say that having hardware for testing is necessary. I don't think you need every possible device but certainly ones that cover the features that your app uses.
It depends on features you need.
Example of things you can't test in the simulator:
Push notifications
Performance of an OpenGL game (usually you need a wide set of device to test OpenGL)
The simulator can be used for development, but the simulator is not relevant for efficiency. It is very recommended to testing on a real device too. Some of the services can not be developed on the simulator:
the push notifications
in-app purchase
iCloud services
And you know, that the iPhone 3G is not able to be updated for the lastest iOS (your iPad is able).
The first answer is YES, you need hardware as there are differences between the behaviour of the simulator and the devices. They won't always act the same as the simulator is a bit more forgiving than the device.
For example the simulator will find files (images/sounds/models etc.) even if the case is different between the request and the file name, the device will not find them. And there are more.
An other point is whether to buy/have devices to hold different iOS versions. I don't have them all as this is too expensive for me but I can say that this is a problem. No matter how much you will try to consider the differences between the devices you will always miss something and your app might not work or crash on this device.
Still you can consider this question by looking at the apps that you are going to work on. I would say that if your apps don't use the device hardware (camera for example) and don't have features that might cause problems on different devices you will be able to start with out the devices.
Bottom line is that if you want to deploy good working apps, in most cases it will be better if you could test your apps on a variety of devices.
It's not a requirement to have a equipment to test, but certainly very important. You can test FPS of your app, even not containing hand-made OpenGL. All features that you use on your app, like view effects, are tested for sure on a device. Since simulator uses your mac memory, you won't see any side effects from memory shortage. I believe your best chance is to have a iPhone 4 and your iPad 2.
I've got a newbie question about phoneGap and creating apps for iOs.
If my phoneGap app runs in device emulator in xCode and everything is ok, can I be sure that it will work the same way on a real iOS device when I publish it in the appstore?
The XCode simulator does what the name suggest - 'simulates'. It is not identical to the actual hardware, for a number of reasons. Here are just a few of them:
Performance - your computer has much more memory and processing power available than the phone itself. Your app may run fine on the simulator, but quite slow on the device. This is why it's a good idea to run on the device itself, especially if you're doing stuff which could use up a lot of memory.
Missing features - the simulator doesn't allow certain things to be tested, like in app purchase or media/asset management. And obviously you're missing things like the camera, the accelerometers, compass, etc. You can from iOS 5 simulate certain things like the GPS, but nowhere near everything.
Visuals - the simulator runs at your monitor resolution, whereas the phone itself has a much higher DPI display. Things that look readable or fine on the simulator can on device look very different.
If you're not testing your app on an actual device before releasing it to the app store you're doing a disservice to your users - this is Apple's point of view, and one shared by most developers. It's not necessarily what you might want to here, but unfortunately the simulator really is just that - a simulator. You wouldn't want to be in a plane piloted by somebody who had only trained on a simulator. And you probably wouldn't want to use an app that had only been run on the iOS simulator.
Here's what Apple have to say about it in their own documentation:
Although you can do much of your debugging and testing of an iOS application using iOS Simulator, simulation cannot completely match the results of running your application on the target devices; you must test your application on actual devices to ensure that it runs as intended and to tune it for performance on actual hardware.