MaxValue<T>
// 2020.10.15๏ผ
import SwiftUI
// ๐ฆ MaxValue<T: FloatingPoint>
public struct MaxValue<T: FloatingPoint>: PreferenceKey {
// value type
public typealias Value = T?
// default value (nil == not set)
public static var defaultValue: Value { nil }
// โญ๏ธ choose max value
public static func reduce(value: inout Value, nextValue: () -> Value) {
// โญ๏ธ [T?] --(compactMap)--> [T] --(max)--> T?
value = [value, nextValue()].compactMap{ $0 }.max()
}
}
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