WWDC 2017

Table of Contents

What's New in LLVM - Thursday

What's New in LLVM - Thursday

Session video and resources: https://developer.apple.com/videos/play/wwdc2017/411/ Provided by @mihriminaz

Api availability checking

Base OS - deprecated functions/new parameters-functions
Swift 3:
- Unified query syntax in swift #available
New Availability checking in Objective-C - NEW!!!
Compiler warnings
@available to query availability
If (@ available(iOS 11, *)) = required
API_AVAILABILITY() macro for your functions, classes to mark OS support..
__builtin_available for C and C++ for class definitions/functions

All APIs are checked in compile time..

Static Analyzer

3 new checks:
1. NSnumber CFNumberRef
- //No need to check for nil.
- self.photoCount.integerValue > 1
- Early return
- Suspicious coversions NSnumber CFNumberRef = set yes aggressive -> compiler will check
1. dispatch_once()
- Global or static variable..
- NSLock ->
1. NSMutable copy properties
- @property(copy) <= mutation detects.

New Warnings

Capturing parameters in blocks with ARC Opt parameter __Strong * error
Non-prototype declarations in C and objective C Change () -> (void)

C++ Warnings

Renaming a function, structs, constants name all over the places..
Turning a block of code to functions - > adds the parameters as reference typed
Code completion

Features from C++17

auto[…] To decompose std::tuple
initializers in if scope, if it is used later - gives error
advanceDispatch -> new !! => constexpr - an alternative for compile-time dispatch
std::string -> Substrings are copies and can be expensive -> use std::string_view, but it is not safe (it does not have a storage - so can cause issues after free/release)

LTO - Link-time optimization

Clean link, incremental link has better performances
Enable incremental LTO