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How to Do You Want to Reduce the Size of Your iPhone App?

iPhone typically does not allow external storage so developer need to reduce size of iPhone app.

How to Do You Want to Reduce the Size of Your iPhone App?

Thursday September 29, 2016,

6 min Read

We all know that internal storage space in an iPhone device is a matter of concern for the users since unlike Android or other devices iPhone typically does not allow external storage. Naturally, any app taking too much space risks itself to be deleted by the users whenever the device demands to vacate space to allow downloading something or smooth functioning of other apps.

Let us go deeper into the trouble. If you have an iPhone with just cannot 16GB of space, you have too many limitations to face since the OS itself needs 4GB of internal space and the rest is reserved for all other apps. Now, can you do away with stored documents, images and video files? Without being able to take snaps and shoot video and store a document, using iPhone amounts to a lot of compromises, right? So, besides OS you need several GBs of memory for these documents and files. What it comes down to? For a 16GB iPhone user, the available space for apps other than media and docs comes down to a maximum of 8GB or even less. When you are using an iPhone with bigger storage space like 128GB, the OS also consumes more space and you are still bound to face space constraint when the volume of media files become huge.

What is the bottom line then? iPhone developers need to keep their apps lightweight with less demand for consuming internal device memory. How can you reduce app size? Here in this post, we are going to provide you some effective tips for cutting down the app size.

App thinning and its importance

App thinning process refers to the approach of dividing the app codes into little parts. While using the app users can use the app file they need instead of downloading the entire resources of the app. This feature has been launched with iOS 9 update and users updated to iOS 9 or later version can enjoy this feature to keep the app size in check.

What makes app thinning so important for the developers and users? How can it deal with the internal storage problem concerning apps? Well, to get the answers consider the reasons and insights below.

1. Mobile apps are increasingly getting complex with a lot of media and other materials contained in them. The same app can have various different versions with compatible architecture like 32 bit, 64 bit etc. These complexities make an app heavy. With the thinning process, the apps are less complex and deliver the architecture respective user needs.

2. By dividing the whole app into small parts it allows only the required parts of the app consume device features and storage space. Naturally, the app gets faster in performance and makes bigger room for device usage.

Asset slicing

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Image source:

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Asset Slicing is another effective method to reduce the burden of an app on the device storage. Well, the assets of an app are bundled as per the device in use and thus excess load from the entire class of assets are avoided. Look at the below mentioned ways to conduct asset slicing.

1. As per different target devices, you need to create multiple resolutions for the images in use and then the asset catalog will slice the respective image versions that are not needed for the target device.

2. You can use some simulator tool for this. Xcode can develop different variants of the iPhone app for different target devices. It allows testing the app variants locally.


Bitcode is nothing but the intermediate representation of the app code. Thanks to Bitcode you can easily optimize and re-optimize the app number of times without requiring to re-submit the new version every time. Bitcode allows making all changes within the existing app.

On-demand resources and its benefits

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On demand resources Image source:

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On-Demand resources refer to the process in which you only provide users resources that are on demand, not the whole bundle of resources. For large size mobile apps with too many resources, this comes as helpful to avoid memory overload.

How does this work? A resource is represented by a tag and you need to assign a tag to each resource throughout your app building process. Now needful resource is identified through these tags. In this way, there will be Prefetch tags that will only be downloaded when an app is run for the first time. There will be Initial tags to run the app on a smartphone and there will be other tags to download resources conditionally as per user need and predetermined circumstances.

On demand, resources offer an array of benefits for developers. Let us have a look at them.

1. Thanks to this method the iPhone app size can be reduced to a great extent. The decrease in app size helps to optimize the app performance and download speed.

2. On demand, resources help utilization of resources only when they are required: This creates better device level utilization of features and functionalities. The request for new resources is sent as the user progresses in steps.

3. This allows offering a remote storage for resources instead of using the device disk space for all the app resources. Every app has too many resources that are used scarcely or not very frequently. For instance, the app user guide or tutorial can only be needed for first-time users, not for all user scenarios.

4. With on-demand resources, an app can actually integrate too many 3rd party resources pertaining to in-app marketing and advertisement. These 3rd party elements as app resources will also be requested as per the user contexts. Thanks to this an app can afford to be resource-heavy while staying lightweight and fast.

As storage space is a constant problem for iPhone users, lightweight apps adding fewer burdens on disk space generally stay longer on user’s device. Besides being lightweight and optimized for resource utilization, such an approach also helps in boosting the app performance and speed to a great extent. If you need to stay longer in your user’s device and continue to delight him with crisp and fast performance, your app needs to be lightweight and smart in resource management.