ios - 是什么使搜索栏选项所选择的Scope ButtonIndexDidChange执行？

Question

我正在尝试快速学习新的UISearchController。那里还没有太多例子。
我一直在寻找添加范围选项，以便当用户在搜索中选择范围时，列表将被范围过滤。我一直在看编程的iOS 8 O'Reilly书籍，示例。他们有一个示例，其中过滤在一个屏幕中完成。
我意识到实际的搜索将不适用于我拥有的当前范围值。目前我所要做的就是使该功能正常运行。我正在使用此代码测试想法，然后将这些想法移植到我的应用程序中。
如果我输入文本搜索，那么所有功能都可以使用，但是当我尝试使用示波器时，它没有用。这是代码。关于为什么永不调用以下代码的任何提示:

func searchBar(searchBar: UISearchBar, selectedScopeButtonIndexDidChange selectedScope: Int) {
    println("In selectedScopeButtonIndexDidChange")
    updateSearchResultsForSearchController(searcher)
}

这是完整的代码。

import UIKit

class ViewController: UITableViewController, UISearchBarDelegate, UISearchControllerDelegate, UISearchResultsUpdating {


var sectionNames = [String]()
var sectionData = [[String]]()
var originalSectionNames = [String]()
var originalSectionData = [[String]]()
var searcher = UISearchController()
var searching = false

override func prefersStatusBarHidden() -> Bool {
    return true
}

override func viewDidLoad() {
    //super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let s = NSString(contentsOfFile: NSBundle.mainBundle().pathForResource("states", ofType: "txt")!, encoding: NSUTF8StringEncoding, error: nil)!
    let states = s.componentsSeparatedByString("\n") as [String]
    var previous = ""
    for aState in states {
        // get the first letter
        let c = (aState as NSString).substringWithRange(NSMakeRange(0,1))
        // only add a letter to sectionNames when it's a different letter
        if c != previous {
            previous = c
            self.sectionNames.append( c.uppercaseString )
            // and in that case also add new subarray to our array of subarrays
            self.sectionData.append( [String]() )
        }
        sectionData[sectionData.count-1].append( aState )
    }
    self.tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: "Cell")
    self.tableView.registerClass(UITableViewHeaderFooterView.self, forHeaderFooterViewReuseIdentifier: "Header")

    self.tableView.sectionIndexColor = UIColor.whiteColor()
    self.tableView.sectionIndexBackgroundColor = UIColor.redColor()
    // self.tableView.sectionIndexTrackingBackgroundColor = UIColor.blueColor()
    // self.tableView.backgroundColor = UIColor.yellowColor()
    self.tableView.backgroundView = { // this will fix it
        let v = UIView()
        v.backgroundColor = UIColor.yellowColor()
        return v
        }()

    // in this version, we take the total opposite approach:
    // we don't present any extra view at all!
    // we already have a table, so why not just filter the very same table?
    // to do so, pass nil as the search results controller,
    // and tell the search controller not to insert a dimming view

    // keep copies of the original data
    self.originalSectionData = self.sectionData
    self.originalSectionNames = self.sectionNames
    let searcher = UISearchController(searchResultsController:nil)
    self.searcher = searcher
    searcher.dimsBackgroundDuringPresentation = false
    searcher.searchResultsUpdater = self
    searcher.delegate = self
    // put the search controller's search bar into the interface
    let b = searcher.searchBar
    b.sizeToFit() // crucial, trust me on this one
    b.autocapitalizationType = .None
    b.scopeButtonTitles = ["All", "S", "X"] // won't show in the table
    **b.delegate = self**
    self.tableView.tableHeaderView = b
    self.tableView.reloadData()
    //self.tableView.scrollToRowAtIndexPath(
    //    NSIndexPath(forRow: 0, inSection: 0),
    //    atScrollPosition:.Top, animated:false)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return self.sectionNames.count
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.sectionData[section].count
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell
    let s = self.sectionData[indexPath.section][indexPath.row]
    cell.textLabel!.text = s

    // this part is not in the book, it's just for fun
    var stateName = s
    stateName = stateName.lowercaseString
    stateName = stateName.stringByReplacingOccurrencesOfString(" ", withString:"")
    stateName = "flag_\(stateName).gif"
    let im = UIImage(named: stateName)
    cell.imageView!.image = im

    return cell
}

override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    let h = tableView.dequeueReusableHeaderFooterViewWithIdentifier("Header") as UITableViewHeaderFooterView
    if h.tintColor != UIColor.redColor() {
        h.tintColor = UIColor.redColor() // invisible marker, tee-hee
        h.backgroundView = UIView()
        h.backgroundView!.backgroundColor = UIColor.blackColor()
        let lab = UILabel()
        lab.tag = 1
        lab.font = UIFont(name:"Georgia-Bold", size:22)
        lab.textColor = UIColor.greenColor()
        lab.backgroundColor = UIColor.clearColor()
        h.contentView.addSubview(lab)
        let v = UIImageView()
        v.tag = 2
        v.backgroundColor = UIColor.blackColor()
        v.image = UIImage(named:"us_flag_small.gif")
        h.contentView.addSubview(v)
        lab.setTranslatesAutoresizingMaskIntoConstraints(false)
        v.setTranslatesAutoresizingMaskIntoConstraints(false)
        h.contentView.addConstraints(
            NSLayoutConstraint.constraintsWithVisualFormat("H:|-5-[lab(25)]-10-[v(40)]",
                options:nil, metrics:nil, views:["v":v, "lab":lab]))
        h.contentView.addConstraints(
            NSLayoutConstraint.constraintsWithVisualFormat("V:|[v]|",
                options:nil, metrics:nil, views:["v":v]))
        h.contentView.addConstraints(
            NSLayoutConstraint.constraintsWithVisualFormat("V:|[lab]|",
                options:nil, metrics:nil, views:["lab":lab]))
    }
    let lab = h.contentView.viewWithTag(1) as UILabel
    lab.text = self.sectionNames[section]
    return h
}

// much nicer without section index during search
override func sectionIndexTitlesForTableView(tableView: UITableView) -> [AnyObject]! {
    return self.searching ? nil : self.sectionNames
}

func searchBar(searchBar: UISearchBar, selectedScopeButtonIndexDidChange selectedScope: Int) {
    println("In selectedScopeButtonIndexDidChange")
    updateSearchResultsForSearchController(searcher)
}

func updateSearchResultsForSearchController(searchController: UISearchController) {
    let sb = searchController.searchBar
    let target = sb.text
    println("target is: \(target)")
    if target == "" {
        self.sectionNames = self.originalSectionNames
        self.sectionData = self.originalSectionData
        self.tableView.reloadData()
        return
    }
    // we have a target string
    self.sectionData = self.originalSectionData.map {
        $0.filter {
            let options = NSStringCompareOptions.CaseInsensitiveSearch
            let found = $0.rangeOfString(target, options: options)
            return (found != nil)
        }
        }.filter {$0.count > 0} // is Swift cool or what?
    self.sectionNames = self.sectionData.map {prefix($0[0],1)}
    self.tableView.reloadData()
}

}

Answer 1

这个问题的答案是添加:

b.delegate = self

进入viewDidLoad()部分。

我已经添加了新行，更新了上面的代码。