Swift 3.0 是 Swift 宣布开源后的首页主要发行版本，包含众多关于核心语言以及标准库的主要改进和优化，同时包含 Swift 在 Linux 上移植的版本，以及官方首个 Swift Package Manager 版本。

Swift 3.0 是一个主要语言发行版本，在源码上与 Swift 2.2 和 2.3 并不兼容，包含了如下的语言特性的变化：

• SE-0002: Removing currying func declaration syntax

• SE-0003: Removing var from Function Parameters

• SE-0004: Remove the ++ and -- operators

• SE-0005: Better Translation of Objective-C APIs Into Swift

• SE-0006: Apply API Guidelines to the Standard Library

• SE-0007: Remove C-style for-loops with conditions and incrementers

• SE-0008: Add a Lazy flatMap for Sequences of Optionals

• SE-0016: Adding initializers to Int and UInt to convert from UnsafePointer and UnsafeMutablePointer

• SE-0017: Change Unmanaged to use UnsafePointer

• SE-0019: Swift Testing

• SE-0023: API Design Guidelines

• SE-0025: Scoped Access Level

• SE-0029: Remove implicit tuple splat behavior from function applications

• SE-0031: Adjusting inout Declarations for Type Decoration

• SE-0032: Add first(where:) method to SequenceType

• SE-0033: Import Objective-C Constants as Swift Types

• SE-0034: Disambiguating Line Control Statements from Debugging Identifiers

• SE-0035: Limiting inout capture to @noescape contexts

• SE-0036: Requiring Leading Dot Prefixes for Enum Instance Member Implementations

• SE-0037: Clarify interaction between comments & operators

• SE-0038: Package Manager C Language Target Support

• SE-0039: Modernizing Playground Literals

• SE-0040: Replacing Equal Signs with Colons For Attribute Arguments

• SE-0043: Declare variables in ‘case’ labels with multiple patterns

• SE-0044: Import as Member

• SE-0046: Establish consistent label behavior across all parameters including first labels

• SE-0047: Defaulting non-Void functions so they warn on unused results

• SE-0048: Generic Type Aliases

• SE-0049: Move @noescape and @autoclosure to be type attributes

• SE-0052: Change IteratorType post-nil guarantee

• SE-0053: Remove explicit use of let from Function Parameters

• SE-0054: Abolish ImplicitlyUnwrappedOptional type

• SE-0055: Make unsafe pointer nullability explicit using Optional

• SE-0057: Importing Objective-C Lightweight Generics

• SE-0059: Update API Naming Guidelines and Rewrite Set APIs Accordingly

• SE-0060: Enforcing order of defaulted parameters

• SE-0061: Add Generic Result and Error Handling to autoreleasepool()

• SE-0062: Referencing Objective-C key-paths

• SE-0063: SwiftPM System Module Search Paths

• SE-0064: Referencing the Objective-C selector of property getters and setters

• SE-0065: A New Model For Collections and Indices

• SE-0066: Standardize function type argument syntax to require parentheses

• SE-0067: Enhanced Floating Point Protocols

• SE-0069: Mutability and Foundation Value Types

• SE-0070: Make Optional Requirements Objective-C-only

• SE-0071: Allow (most) keywords in member references

• SE-0072: Fully eliminate implicit bridging conversions from Swift

• SE-0076: Add overrides taking an UnsafePointer source to non-destructive copying methods on UnsafeMutablePointer

• SE-0077: Improved operator declarations

• SE-0081: Move where clause to end of declaration

• SE-0085: Package Manager Command Names

• SE-0086: Drop NS Prefix in Swift Foundation

• SE-0088: Modernize libdispatch for Swift 3 naming conventions

• SE-0089: Renaming String.init<T>(_: T)

• SE-0091: Improving operator requirements in protocols

• SE-0092: Typealiases in protocols and protocol extensions

• SE-0093: Adding a public base property to slices

• SE-0094: Add sequence(first:next:) and sequence(state:next:) to the stdlib

• SE-0095: Replace protocol<P1,P2> syntax with P1 & P2 syntax

• SE-0096: Converting dynamicType from a property to an operator

• SE-0099: Restructuring Condition Clauses

• SE-0101: Reconfiguring sizeof and related functions into a unified MemoryLayoutstruct

• SE-0102: Remove @noreturn attribute and introduce an empty Never type

• SE-0103: Make non-escaping closures the default

• SE-0106: Add a macOS Alias for the OSX Platform Configuration Test

• SE-0107: UnsafeRawPointer API

• SE-0109: Remove the Boolean protocol

• SE-0111: Remove type system significance of function argument labels

• SE-0112: Improved NSError Bridging

• SE-0113: Add integral rounding functions to FloatingPoint

• SE-0114: Updating Buffer "Value" Names to "Header" Names

• SE-0115: Rename Literal Syntax Protocols

• SE-0116: Import Objective-C id as Swift Any type

• SE-0117: Allow distinguishing between public access and public overridability

• SE-0118: Closure Parameter Names and Labels

• SE-0120: Revise partition Method Signature

• SE-0121: Remove Optional Comparison Operators

• SE-0124: Int.init(ObjectIdentifier) and UInt.init(ObjectIdentifier)should have a bitPattern: label

• SE-0125: Remove NonObjectiveCBase and isUniquelyReferenced

• SE-0127: Cleaning up stdlib Pointer and Buffer Routines

• SE-0128: Change failable UnicodeScalar initializers to failable

• SE-0129: Package Manager Test Naming Conventions

• SE-0130: Replace repeating Character and UnicodeScalar forms of String.init

• SE-0131: Add AnyHashable to the standard library

• SE-0133: Rename flatten() to joined()

• SE-0134: Rename two UTF8-related properties on String

• SE-0135: Package Manager Support for Differentiating Packages by Swift version

• SE-0136: Memory Layout of Values

• SE-0137: Avoiding Lock-In to Legacy Protocol Designs

官方发行说明：https://swift.org/blog/swift-3-0-released/