Preview
Take the interface apart
Spread the layers apart in 3D and turn them with the trackpad to see what sits behind what. Collapse a subtree in the list and it folds back into one.
The preview →Skip to contentNew1.2: environment overrides, virtual nodes, Open in Xcode →
Inspect iOS interfaces, layer by layer.
Cutaway is a free Mac app that looks inside your running iOS app: every layer of the interface in 2D or spread apart in 3D, with its attributes and Auto Layout constraints. Change a value, and the app changes with it.
Three steps to your first inspection
About ten minutes, most of it waiting for a build.
1
Add CutawayServer
Add the Swift package to your iOS app and start it at launch. It goes into Debug builds only.
CutawayServer.start()2
Run your app
In the Simulator, or on an iPhone or iPad connected to your Mac with a cable.
3
Open Cutaway
Your app appears in the list within a few seconds. Choose it, and its layers arrive.
See how the interface is really built
Everything below works in the Simulator and on a device over USB, with any app that includes CutawayServer.
Measuring
Measure without a ruler
Select a layer, hold ⌥ and point at another, in the preview or in the layer list. The distances appear in points, in 2D and in 3D.
Measuring →Attributes
Change it while it runs
Edit text, colors, opacity, insets and more. Each change is applied in the running app at once, and ⌘Z undoes it.
Attributes →Auto Layout
Follow the constraints
See every constraint that refers to a view, which ones are not in effect, and where the other end is. Click the other end to go to it.
Constraints →EnvironmentNeeds CutawayServer 1.2
Try dark mode and larger text
Override the app’s appearance, text size, layout direction and size classes from the toolbar, and the preview follows, without opening the Simulator’s settings.
Environment →Archives
Keep what you found
Save an inspection as a .cutaway file and open it later on any Mac, without the device: the tree, screenshots, attributes and constraints are all there.
Archives and export →Open in XcodeJump from a class to its declaration in your project.Copy LLDB CommandPaste a command that reaches the same object in the debugger.Filter and focusFind a layer by name, then show only its subtree.Your app’s own detailsAttribute groups, color names and virtual nodes from your code.Export as PNGA layer’s image, alone or with its sublayers, at the device’s scale.Five languagesEnglish, Simplified and Traditional Chinese, Japanese and Korean.
Fast with ten thousand layers
Every full test run on the development Mac holds Cutaway to these limits, on a generated tree of 10,000 layers shaped like a real app.
2 sfrom the tree arriving to the list on screen
16 msfor a new frame while you turn the camera
100 msfrom selecting a row to the preview and inspector following
Stays between your Mac and your app
Privacy and security →- Cutaway talks to simulators over the loopback address and to devices over the USB cable, and to nothing else.
- No account, no analytics, no crash reports. Checking for updates asks GitHub for the list of releases and sends nothing about your Mac.
- CutawayServer listens on 127.0.0.1 only and is left out of Release builds unless you opt in.
Three open-source parts
The Mac app and the iOS SDK share no code, only a versioned protocol, so either side can be read, tested or replaced on its own.
Cutawayon your Mac
Cutaway ProtocolTCP over the loopback address,
or USB through usbmuxd
or USB through usbmuxd
Your appCutawayServerSimulator or USB device
Cutaway
The macOS app. Finds your apps, draws their layers and edits their attributes. Swift, AppKit and Metal.
CutawayServer
The iOS SDK you add to your app. Captures layers, images and attributes when Cutaway asks. Pure Swift, no dependencies.
Cutaway Protocol
The FlatBuffers protocol between them: a numbered specification, the schema, and fixtures for testing either end.