The top of tableView has some empty area - ios

Question

The issue occurs as the pic .
at the top of tableView has some empty area
The interface is that viewController(embed in navigationController).I put one tableView on it.And construct its constraints.But run the code ,and the issue occurs .I wanna try to use two methods to solve it ,but no any changes.
self.automaticallyAdjustsScrollViewInsets = true
I adjust the constraints of tableView to superView,I set the constraint of top to -100,it works well.
The code as below:
import UIKit
import CoreData
class ViewController: UIViewController {
#IBOutlet weak var tableView: UITableView!
var people:[NSManagedObject] = []
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
self.title = "My book"
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
return
}
let managedContext = appDelegate.persistentContainer.viewContext
let fetchRequest = NSFetchRequest<NSManagedObject>(entityName:"Person")
do {
people = try managedContext.fetch(fetchRequest)
}catch let error as NSError {
print("Cannot fetch \(error),\(error.userInfo)")
}
}
#IBAction func addName(_ sender: AnyObject) {
let alert = UIAlertController(title: "New name", message: "Add a name", preferredStyle: .alert)
let saveAction = UIAlertAction(title: "Save", style: .default) { [unowned self] action in
guard let textField = alert.textFields?.first,
let nameToSave = textField.text else {return
}
self.save(name: nameToSave)
self.tableView.reloadData()
}
let cancelAction = UIAlertAction(title: "Cancel", style: .default)
alert.addTextField()
alert.addAction(saveAction)
alert.addAction(cancelAction)
present(alert,animated: true)
}
func save(name:String) {
guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
return
}
let managedContext = appDelegate.persistentContainer.viewContext
let entity = NSEntityDescription.entity(forEntityName: "Person", in: managedContext)
let person = NSManagedObject(entity: entity!, insertInto: managedContext)
person.setValue(name, forKey: "name")
do {
try managedContext.save()
people.append(person)
}catch let error as NSError {
print("Could not save\(error),\(error.userInfo)")
}
}
}
extension ViewController :UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return people.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let person = people[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
cell.textLabel?.text = person.value(forKey: "name") as? String
return cell
}
}

Answer 1

You should put constraint for the tableView from storyboard and set top space = 0

Answer 2

You can also try setting the edgesForExtendedLayout in your viewDidLoad method:
self.edgesForExtendedLayout = []

Answer 3

try to implement
func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return .min
}