acalism

private var ExtendEdgeInsetsKey: Void?

extension UIButton {

    /// 设置此属性即可扩大响应范围, 分别对应上左下右
    /// 优势：与Auto-Layout无缝配合
    /// 劣势：View Debugger 查看不到增加的响应区域有多大，
    var extendEdgeInsets: UIEdgeInsets {
        get {
            return objc_getAssociatedObject(self, &ExtendEdgeInsetsKey) as? UIEdgeInsets ?? UIEdgeInsets.zero

acalism

extension UIOffset {
    /// 转换为 CGPoint 形式
    var point: CGPoint {
        return CGPoint(x: horizontal, y: vertical)
    }
}

extension CGPoint {
    /// 转换为 UIOffset
    var offset: UIOffset {

acalism

fileprivate protocol _Optional {
    func unwrappedString() -> String
}

extension Optional: _Optional {
    fileprivate func unwrappedString() -> String {
        switch self {
        case .some(let wrapped as _Optional): return wrapped.unwrappedString()
        case .some(let wrapped): return String(describing: wrapped)
        case .none: return String(describing: self)

acalism

import UIKit


// MARK: - FindHostView

protocol FindHostView {
    associatedtype T
    var hostView: T? { get }
}

acalism

// MARK: - UIScrollViewDelegate

// 找到结束滚动事件

    func scrollViewDidEndDragging(_ sv: UIScrollView, willDecelerate decelerate: Bool) {
        if !sv.isDragging, !sv.isDecelerating, !decelerate {
            scrollViewDidEndScroll(sv)
        }
    }

acalism

// 1. URL 转为 URLComponents 时，什么时候会变成 nil
// 2. URLComponents 转为 URL 时，什么时候会变成 nil
// 3. URL 协议后不带双斜杠时，为什么 host 会变成 path（如下例）


let str = "http:im.qq.com" // "mailto:[email protected]"
if let url = URL(string: str), let uc = URLComponents(url: url, resolvingAgainstBaseURL: true) {
    print(url)
    print(uc, uc.url!)
    print(uc.scheme!, uc.path)

acalism

// 这两个方法有冲突（调用时无法区分），除非其中一个去掉IndexPath后的问号

/// 不能有默认参数 nil，因为inout不能操作常量
func shouldChange(indexPath: inout IndexPath?) -> Bool {
    indexPath = IndexPath(item: 0, section: 1)
    return true
}

/// 可以有默认参数 nil，
func shouldChange(indexPath: UnsafeMutablePointer<IndexPath?>? = nil) -> Bool {

acalism

extension WKWebView {
    /// sync version
    ///
    /// - Parameters:
    ///   - js: 要执行的javascript代码
    ///   - timeout: 限时返回（单位秒），0表示不限时
    /// - Returns: 执行结果
    func evaluatingJavaScript(_ js: String, timeout: TimeInterval = 0) -> Any? {
        var res: Any? = nil
        var finish = false

acalism

// textField included by a cell, and the cell included by a scrollView

override func willMove(toWindow newWindow: UIWindow?) {
    super.willMove(toWindow: newWindow)
    if newWindow == nil {
        NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillChangeFrame, object: nil)
    } else {
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardFrameWillChange(_:)), name: .UIKeyboardWillChangeFrame, object: nil)
    }
}

acalism

po view.recersiveDescription 可以输出整个view层次
po Thread.callStackSymbols   输出栈信息