Minimum Requirements

We officially support iOS 11.0 as iOS Deployment Target. You can try older versions but there are no guarantees it will work as expected.

Note on Sinch.xcframework File Size vs. Linked Size

The Sinch.xcframework file includes a FAT-binary containing the architectures arm64 and x86_64. When linking an application target against the Sinch.xcframework targeting an iOS device, it will add a approximately 9.5MB for arm64.

Restrictions on User IDs

User IDs must not be longer than 255 bytes, must only contain URL-safe characters, and restricted to the following character set:


If you need to use User IDs containing characters outside the allowed set above, you could consider base64-encoding the raw User IDs using a URL-safe base64 alphabet as described in https://tools.ietf.org/html/rfc4648#section-5). Please note how the allowed character set overlaps with the URL-safe base64 alphabet, but does NOT allow characters in the non-URL-safe alphabet, example / (forward slash) and + (plus sign).

Local Database File

Sinch SDK needs a local database file to operate properly. It's located in the application support directory (NSApplicationSupportDirectory) in the sinch/db/rtc/ subfolder. The application must not delete this folder.


The Sinch SDK client uploads statistics to the Sinch servers at the end of a call, a call failure, or similar event. The statistics are used for monitoring of network status, call quality, and other aspects regarding the general quality of the service.

Some of the information is not anonymous and may be associated with the User ID call participants.

The statistics upload is done by the client in the background.

Xcode and Bitcode Intermediate Representation

The Sinch SDK supports Bitcode intermediate representation.

App Extensions

App Extensions is a feature introduced in iOS 8. App extensions are compiled into executables that are separate from the main application executable. The Sinch SDK are using parts of the iOS SDK APIs that are unavailable to app extensions, thus it’s not supported to use the Sinch SDK in an app extension.

Linking Against the C++ Standard Library

Since Sinch SDK version 3.4.0, it's required to link against libc++. Though if your application is also dependent on libstdc++ (which is now considered deprecated by Apple for use on iOS), you can actually link against both libc++ and libstdc++ by passing the following linker flags:

  • Other Linker Flags -> -ObjC -Xlinker -lc++ -Xlinker -lstdc++

SDK Static and Dynamic Libraries

The SDK is available as both a static library and a dynamic library; note that if you switch from using the dynamic to the static version of the SDK, you may have to:

Encryption Export Regulations

Please see Encryption and Export Administration Regulations (EAR) and ensure that, if applicable, your application is registered for encryption regulations.

Deprecated Features and APIs

Active Connection in Background

Apple has since iOS 10 discontinued support for maintaining a VoIP control connection alive via -[UIApplication setKeepAliveTimeout:handler:]. Attempting to use this method on an iOS device running iOS 10 results in the following warning log: Legacy VoIP background mode is deprecated and no longer supported. The Sinch feature Active connection in background was using the keep alive handler API and is as a consequence no longer supported on iOS. it's recommended to use VoIP Push Notifications and CallKit to achieve the equivalent functionality.

Missed Call Push Notifications

Sinch SDK primarily use VoIP push notifications. Since iOS 13, Apple and iOS imposed stricter limitations and requirements on how each VoIP push notification that an application receive must be reported to CallKit as an incoming call. This has the implication that Sinch SDK no longer supports separate "Missed Call" push notifications.

We recommend using your own non-VoIP push notification mechanism to deliver "Missed Call" push notifications.

Please also see Apple Developer documentation on this topic.

We'd love to hear from you!
Rate this content:
Still have a question?
Ask the community.