Writing High-Performance Swift Code

• Enabling Optimizations
• Whole Module Optimizations (WMO)
• Reducing Dynamic Dispatch
• Dynamic Dispatch
• Advice: Use 'final' when you know the declaration does not need to be overridden
• Advice: Use 'private' and 'fileprivate' when declaration does not need to be accessed outside of file
• Advice: If WMO is enabled, use 'internal' when a declaration does not need to be accessed outside of module
• Using Container Types Efficiently
• Advice: Use value types in Array
• Advice: Use ContiguousArray with reference types when NSArray bridging is unnecessary
• Advice: Use inplace mutation instead of object-reassignment
• Wrapping operations
• Advice: Use wrapping integer arithmetic when you can prove that overflow cannot occur
• Generics
• Advice: Put generic declarations in the same module where they are used
• The cost of large Swift values
• Advice: Use copy-on-write semantics for large values
• Unsafe code
• Advice: Use unmanaged references to avoid reference counting overhead
• Protocols
• Advice: Mark protocols that are only satisfied by classes as class-protocols
• The Cost of Let/Var when Captured by Escaping Closures
• Advice: Pass var as an inout if closure not actually escaping
• Unsupported Optimization Attributes

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