Xcode

Practical reference for Xcode's project structure, Interface Builder, debugging, and simulators.

Project Structure

.xcodeproj — a single project’s build settings, targets, and file references.
.xcworkspace — groups multiple projects (e.g. an app + its CocoaPods dependencies); open this instead of the .xcodeproj when it exists.
Targets — a target defines how a product (app, framework, extension) is built: sources, resources, and build settings.
Schemes — a scheme ties a target to a build configuration (Debug/ Release) and run/test/archive actions.
Info.plist — per-target configuration (bundle ID, permissions, supported orientations, etc).

.storyboard / .xib — visual layouts for UIKit; SwiftUI views are plain Swift files instead.
Auto Layout — constraints define position/size relative to other views; select a view and use the constraint bar at the bottom-right of the canvas.
Outlets & Actions — Ctrl+drag from a view to code to create an @IBOutlet (reference) or @IBAction (event handler).
Cmd+Option+Return — toggle the SwiftUI canvas/preview alongside code.

Cmd+Y — toggle breakpoints on/off without removing them.
Cmd+\ — add a breakpoint at the current line.
LLDB console — available at the bottom of the debug area; use po <expression> to print an object’s description.
View Debugging → Capture View Hierarchy — inspect the live view tree and constraints of a running app.
Breakpoint navigator (Cmd+8) — manage, disable, or add conditions/actions to breakpoints.

Cmd+Shift+H — go to Home screen.
Cmd+K — toggle the software keyboard.
Cmd+Shift+4-style screenshots via Device → Trigger Screenshot, or Cmd+S inside the Simulator app.
Device → Erase All Content and Settings — reset a simulator to a clean state.
xcrun simctl list devices — list simulators from the command line.
xcrun simctl boot "<name>" — boot a specific simulator by name.

Build Configurations — Debug and Release by default; control optimization level, DEBUG flags, and code signing per configuration.
Product → Clean Build Folder (Cmd+Shift+K) — clear cached build artifacts when a build behaves inconsistently.
Build Phases — per-target steps (compile sources, link binaries, copy resources, run scripts) shown in the target’s settings.
xcodebuild -list — inspect a project’s schemes, targets, and configurations from the command line.