Swift Language (Unsafe) Buffer Pointers Practical Use-Case for Buffer Pointers
Example
Deconstructing the use of an unsafe pointer in the Swift library method;
public init?(validatingUTF8 cString: UnsafePointer<CChar>)
Purpose:
Creates a new string by copying and validating the null-terminated UTF-8 data referenced by the given pointer.
This initializer does not try to repair ill-formed UTF-8 code unit sequences. If any are found, the result of the initializer is nil. The following example calls this initializer with pointers to the contents of two different CChar arrays---the first with well-formed UTF-8 code unit sequences and the second with an ill-formed sequence at
the end.
Source, Apple Inc., Swift 3 header file (For header access: In Playground, Cmd+Click on the word Swift) in the line of code:
import Swift
let validUTF8: [CChar] = [67, 97, 102, -61, -87, 0]
validUTF8.withUnsafeBufferPointer { ptr in
let s = String(validatingUTF8: ptr.baseAddress!)
print(s as Any)
}
// Prints "Optional(Café)"
let invalidUTF8: [CChar] = [67, 97, 102, -61, 0]
invalidUTF8.withUnsafeBufferPointer { ptr in
let s = String(validatingUTF8: ptr.baseAddress!)
print(s as Any)
}
// Prints "nil"
(Source, Apple Inc., Swift Header File Example)
