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113Optional is an enum
114Optional pattern matching in switch
115if case let x? = value
116Optional binding with shorthand if let x
117Multiple optional bindings in one condition
118guard let with shadowing
119Implicitly unwrapped optionals
120Optional chaining on method calls
121Optional chaining with assignment
122Optional chaining through subscripts
123Optional map
124Optional flatMap
125Optional.zip-style combining with tuples
126Comparing optionals with ==
127Optional comparison with nil literal
128Double optionals (Int??)
129Optional try? flattening in Swift 5
130Nil-coalescing chains
131Nil-coalescing with throwing autoclosures
132Optional in Codable
133Optional properties and lazy initialization
134Optional protocol requirements with @objc
135Optional closures and calling them
136Unwrapping with ! and fatalError messages
137Optional.unsafelyUnwrapped
138compactMap to drop nils
139Optional sequences and for case let
140Optionals and Equatable synthesis
141Optionals in generics constraints
142Result vs Optional vs throws
143String is a collection of Characters
144Unicode scalars vs grapheme clusters
145String.Index and why Int subscripts are missing
146index(after:) and index(before:)
147index(_:offsetBy:) and limitedBy
148Substring and memory sharing
149Converting Substring to String
150String.count versus utf8.count
151unicodeScalars view
152utf8 and utf16 views
153Multiline string literals
154Raw string literals with #
155String interpolation customization
156DefaultStringInterpolation
157ExpressibleByStringInterpolation
158String comparison and canonical equivalence
159hasPrefix and hasSuffix
160contains(_:) for substrings
161split(separator:)
162components(separatedBy:)
163replacingOccurrences(of:with:)
164trimmingCharacters(in:)
165String(format:)
166Character properties isLetter and isNumber
167Character.asciiValue
168lowercased and uppercased
169capitalized and localized capitalization
170String ranges and replaceSubrange
171insert and remove on strings
172String.Encoding conversions
173Data to String conversion
174localizedStandardCompare
175Regex literals in Swift 5.7
176Regex builder DSL
177firstMatch and wholeMatch
178Regex captures and typed outputs
179RegexComponent and custom components
180String.contains(Regex)
181AttributedString basics
182AttributedString attributes and runs
183Markdown in AttributedString
184String Catalogs and LocalizedStringResource
185StaticString
186String.withCString
187String.init(describing:) and reflecting
188CustomStringConvertible
189CustomDebugStringConvertible
190TextOutputStream
191Integer type family
192Int8 Int16 Int32 Int64 ranges
193UInt types and when to use them
194Overflow trapping behavior
195Overflow operators &+ &- &*
196addingReportingOverflow
197multipliedFullWidth
198Bitwise operators & | ^ ~
199Bit shifting operators
200Int.bitWidth and nonzeroBitCount
201leadingZeroBitCount
202Numeric literals with underscores
203Binary octal hex literals
204Double and Float precision
205Float16 on Apple silicon
206Decimal type for currency
207NSDecimalNumber interop
208Double.nan and infinity
209isNaN isInfinite isFinite
210rounded(_:) and FloatingPointRoundingRule
211truncatingRemainder and remainder
212squareRoot and fma
213Double.ulp and nextUp
214pow exp log in Foundation
215Trigonometric functions
216BinaryInteger protocol
217FixedWidthInteger protocol
218BinaryFloatingPoint protocol
219Numeric protocol
220SignedNumeric and magnitude
221Strideable protocol
222stride(from:to:by:)
223Int(exactly:)
224Int(truncatingIfNeeded:)
225Int(clamping:)
226Random numbers with Int.random(in:)
227SystemRandomNumberGenerator
228RandomNumberGenerator custom seeding
229Swift Numerics package
230Complex numbers in swift-numerics
231Int128 in Swift 6
232Operator precedence groups
233Custom prefix operators
234Custom infix operators
235Custom postfix operators
236Compound assignment operators
237Range operators ...< and ...
238Ternary conditional operator
239Identity operators === and !==
240Pattern match operator ~=
241Nil-coalescing operator ??
242Operator functions as arguments
243Tuple decomposition
244Named tuple elements
245Tuples as return values
246Tuple comparison
247Tuple as switch subject
248Tuple pattern with where
249Closed range and half-open range types
250PartialRangeFrom and PartialRangeThrough
251RangeExpression protocol
252ClosedRange.contains
253Range overlaps and clamped
254Ranges of Doubles
255CountableRange legacy
256Switch value binding
257Switch where clauses
258Switch compound cases
259fallthrough keyword
260Switch on enums exhaustively
261@unknown default
262Switch on optionals
263Switch expression in Swift 5.9
264if expression in Swift 5.9
265Labeled statements
266break and continue with labels
267for-in with where
268for case pattern
269for-in over dictionaries
270enumerated() iteration
271zip iteration
272reversed() and stride loops
273while let loops
274repeat-while semantics
275defer statements
276Multiple defer ordering
277guard scope exit rules
278#available checks
279#unavailable
280if #available with @available
281Compiler control statements #if
282#if canImport
283#if os and arch
284#if compiler and swift version
285#warning and #error
286#file #line #function
287#fileID and #filePath
288#column and #dsohandle
289Swift 6 language mode flags
290Upcoming feature flags
291Function types
292Parameter labels and underscores
293inout parameters
294inout and copy-in copy-out
295Variadic parameters
296Default argument expressions
297Nested functions
298Returning functions
299Function overloading by type
300Overload resolution rules
301Generic functions
302@discardableResult
303@inlinable
304@inline(__always)
305@_specialize
306Implicit returns
307Multiple return values
308Throwing functions
309rethrows
310Typed throws in Swift 6
311Async functions
312Closure expression syntax
313Shorthand argument names $0
314Closure capture semantics
315Capture lists [weak self]
316Capture lists [unowned self]
317Capturing inout is forbidden
318@escaping annotation
319@autoclosure
320@autoclosure(escaping)
321@Sendable closures
322@MainActor closures
323Non-escaping closure guarantees
324withoutActuallyEscaping
325Closures stored in properties
326Closure retain cycles
327Currying in Swift
328Function composition operators
329callAsFunction
330Key paths as functions
331Trailing closure rules and multiple trailing closures
332Unlabeled trailing closure matching
333Recursion and tail calls
334consuming and borrowing parameters
335sending parameters in Swift 6
336Parameter packs and each
337repeat each expressions
338Variadic generics

113Optional is an enum
114Optional pattern matching in switch
115if case let x? = value
116Optional binding with shorthand if let x
117Multiple optional bindings in one condition
118guard let with shadowing
119Implicitly unwrapped optionals
120Optional chaining on method calls
121Optional chaining with assignment
122Optional chaining through subscripts
123Optional map
124Optional flatMap
125Optional.zip-style combining with tuples
126Comparing optionals with ==
127Optional comparison with nil literal
128Double optionals (Int??)
129Optional try? flattening in Swift 5
130Nil-coalescing chains
131Nil-coalescing with throwing autoclosures
132Optional in Codable
133Optional properties and lazy initialization
134Optional protocol requirements with @objc
135Optional closures and calling them
136Unwrapping with ! and fatalError messages
137Optional.unsafelyUnwrapped
138compactMap to drop nils
139Optional sequences and for case let
140Optionals and Equatable synthesis
141Optionals in generics constraints
142Result vs Optional vs throws
143String is a collection of Characters
144Unicode scalars vs grapheme clusters
145String.Index and why Int subscripts are missing
146index(after:) and index(before:)
147index(_:offsetBy:) and limitedBy
148Substring and memory sharing
149Converting Substring to String
150String.count versus utf8.count
151unicodeScalars view
152utf8 and utf16 views
153Multiline string literals
154Raw string literals with #
155String interpolation customization
156DefaultStringInterpolation
157ExpressibleByStringInterpolation
158String comparison and canonical equivalence
159hasPrefix and hasSuffix
160contains(_:) for substrings
161split(separator:)
162components(separatedBy:)
163replacingOccurrences(of:with:)
164trimmingCharacters(in:)
165String(format:)
166Character properties isLetter and isNumber
167Character.asciiValue
168lowercased and uppercased
169capitalized and localized capitalization
170String ranges and replaceSubrange
171insert and remove on strings
172String.Encoding conversions
173Data to String conversion
174localizedStandardCompare
175Regex literals in Swift 5.7
176Regex builder DSL
177firstMatch and wholeMatch
178Regex captures and typed outputs
179RegexComponent and custom components
180String.contains(Regex)
181AttributedString basics
182AttributedString attributes and runs
183Markdown in AttributedString
184String Catalogs and LocalizedStringResource
185StaticString
186String.withCString
187String.init(describing:) and reflecting
188CustomStringConvertible
189CustomDebugStringConvertible
190TextOutputStream
191Integer type family
192Int8 Int16 Int32 Int64 ranges
193UInt types and when to use them
194Overflow trapping behavior
195Overflow operators &+ &- &*
196addingReportingOverflow
197multipliedFullWidth
198Bitwise operators & | ^ ~
199Bit shifting operators
200Int.bitWidth and nonzeroBitCount
201leadingZeroBitCount
202Numeric literals with underscores
203Binary octal hex literals
204Double and Float precision
205Float16 on Apple silicon
206Decimal type for currency
207NSDecimalNumber interop
208Double.nan and infinity
209isNaN isInfinite isFinite
210rounded(_:) and FloatingPointRoundingRule
211truncatingRemainder and remainder
212squareRoot and fma
213Double.ulp and nextUp
214pow exp log in Foundation
215Trigonometric functions
216BinaryInteger protocol
217FixedWidthInteger protocol
218BinaryFloatingPoint protocol
219Numeric protocol
220SignedNumeric and magnitude
221Strideable protocol
222stride(from:to:by:)
223Int(exactly:)
224Int(truncatingIfNeeded:)
225Int(clamping:)
226Random numbers with Int.random(in:)
227SystemRandomNumberGenerator
228RandomNumberGenerator custom seeding
229Swift Numerics package
230Complex numbers in swift-numerics
231Int128 in Swift 6
232Operator precedence groups
233Custom prefix operators
234Custom infix operators
235Custom postfix operators
236Compound assignment operators
237Range operators ...< and ...
238Ternary conditional operator
239Identity operators === and !==
240Pattern match operator ~=
241Nil-coalescing operator ??
242Operator functions as arguments
243Tuple decomposition
244Named tuple elements
245Tuples as return values
246Tuple comparison
247Tuple as switch subject
248Tuple pattern with where
249Closed range and half-open range types
250PartialRangeFrom and PartialRangeThrough
251RangeExpression protocol
252ClosedRange.contains
253Range overlaps and clamped
254Ranges of Doubles
255CountableRange legacy
256Switch value binding
257Switch where clauses
258Switch compound cases
259fallthrough keyword
260Switch on enums exhaustively
261@unknown default
262Switch on optionals
263Switch expression in Swift 5.9
264if expression in Swift 5.9
265Labeled statements
266break and continue with labels
267for-in with where
268for case pattern
269for-in over dictionaries
270enumerated() iteration
271zip iteration
272reversed() and stride loops
273while let loops
274repeat-while semantics
275defer statements
276Multiple defer ordering
277guard scope exit rules
278#available checks
279#unavailable
280if #available with @available
281Compiler control statements #if
282#if canImport
283#if os and arch
284#if compiler and swift version
285#warning and #error
286#file #line #function
287#fileID and #filePath
288#column and #dsohandle
289Swift 6 language mode flags
290Upcoming feature flags
291Function types
292Parameter labels and underscores
293inout parameters
294inout and copy-in copy-out
295Variadic parameters
296Default argument expressions
297Nested functions
298Returning functions
299Function overloading by type
300Overload resolution rules
301Generic functions
302@discardableResult
303@inlinable
304@inline(__always)
305@_specialize
306Implicit returns
307Multiple return values
308Throwing functions
309rethrows
310Typed throws in Swift 6
311Async functions
312Closure expression syntax
313Shorthand argument names $0
314Closure capture semantics
315Capture lists [weak self]
316Capture lists [unowned self]
317Capturing inout is forbidden
318@escaping annotation
319@autoclosure
320@autoclosure(escaping)
321@Sendable closures
322@MainActor closures
323Non-escaping closure guarantees
324withoutActuallyEscaping
325Closures stored in properties
326Closure retain cycles
327Currying in Swift
328Function composition operators
329callAsFunction
330Key paths as functions
331Trailing closure rules and multiple trailing closures
332Unlabeled trailing closure matching
333Recursion and tail calls
334consuming and borrowing parameters
335sending parameters in Swift 6
336Parameter packs and each
337repeat each expressions
338Variadic generics

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Lesson 124 of 2,511·7. Swift Language in DepthFree lesson

Optional flatMap

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