threema-ios/Threema/StdTypeHelper.swift

//  _____ _
// |_   _| |_  _ _ ___ ___ _ __  __ _
//   | | | ' \| '_/ -_) -_) '  \/ _` |_
//   |_| |_||_|_| \___\___|_|_|_\__,_(_)
//
// Threema iOS Client
// Copyright (c) 2018-2020 Threema GmbH
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License, version 3,
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

import Foundation

extension Bool {
    // Create a boolean from an optional string
    public init?(_ value: String?) {
        guard let value = value else {
            return nil
        }
        self.init(value)
    }
}

extension Double {
    // Create a double from an optional string
    public init?(_ value: String?) {
        guard let value = value else {
            return nil
        }
        self.init(value)
    }
}

extension UInt64 {
    // Create a uint64 from an optional string
    public init?(_ value: String?) {
        guard let value = value else {
            return nil
        }
        self.init(value)
    }
}

extension String {
    // Extract a character from a string
    // Example: "foo"[1] == "o"
    subscript (i: Int) -> Character {
        return self[index(startIndex, offsetBy: i)]
    }
}