WWDC 2019 Debugging in Xcode11

Device Conditions and Environment Overrides

Device Conditions

Device-wide induced condition
Managed by Xcode
Tied to Xcode device connection
iOS status bar indicates when a condition is active
Can be stopped on deivce

Thermal state condition

Raises thermal state to - fair, serious, or critical
So you can reliably
·Understand app behavior under these elevated states
·Debug and verify your handling of thermal state changes

Network link condition

Real world profiles simulating network conditions
·High latency
·Low bandwidth
·High packet loss
·Slow DNS response
So you can reliably
·Understand and debug app behavior under various network conditions

Environment Overrides

Demo

可以设置网络状态和热状态？
可以在底部控制台设置黑暗模式与否
还可以更改控件大小来测试(SwiftUI)

Override runtime environment of debugged app
Overrides instantly
Only affects debugged app
System setting remain unchanged
Supports devices simulator, and previews
Available for all platforms

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Debugging Live Previews

Live previews are debuggable
Workflows for previews
SwiftUI runtime issues

SwiftUI Runtime Issues

Found when process is running
Process continues executing
Details in Issues Navigator
All platforms and run destinations

Demo

直接改代码可以看到bug是否已经修复

可以点击Runtime Issue Breakpoint，在运行过程中执行断点调试

点击Editor-Previews-Refresh来进行刷新

Debugging Workflow

Use contextual menu to start debugging
New debug session for source changes
Keep the same file in main editor

Debugging SwiftUI View Hierarchies

Declarative API
Composition and lightweight modifiers over complex views
Value type semantics
Platform specific views at runtime
interoperability with UIKit and AppKit

SwiftUI 和 UIKit and AppKit可以一起使用

可以在右侧边栏看到具体的UI设定,从而加大找出问题的速度

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View hierarchy in navigator and canvas
Properties and modifiers in inspector
Automatic inspector properties through Swift reflection
Custom inspector properties by adopting CustomReflectable
Support for mixed view hierarchies

View Hierarchy Debugging Improvements

UIWindowScene support
Inspectors
·Trait collections
·Named images
·Symbol images
·Named colors
·Improved constraint details

//More In WWDC
Designing for Advers Network and Temperature Conditions
LLDB: Beyond "po"