Swift设置委托给自己提供EXC_BAD_ACCESS [英] Swift set delegate to self gives EXC_BAD_ACCESS
问题描述
我有一个扩展UITableViewCell的类
import UIKit
协议SwitchCellDelegate {
func switchChanged(switchCell:SwitchCell,state:Bool)
}
class SwitchCell:UITableViewCell {
@IBOutlet var swtSelector:UISwitch
@IBOutlet var lblTitle:UILabel
var delegate:SwitchCellDelegate?
init(style:UITableViewCellStyle,reuseIdentifier:String){
super.init(style:style,reuseIdentifier:reuseIdentifier)
}
@IBAction func switchChanged(){
delegate?.switchChanged(self,state:swtSelector.on)
}
}
然后在ViewController中定义为
class SettingsViewController:UIViewController ,UITableViewDelegate,UITableViewDataSource,SwitchCellDelegate {
并在方法
func tableView(tableView:UITableView !, cellForRowAtIndexPath indexPath:NSIndexPath!) - > UITableViewCell! {
我们有
case 2:
storeCredentialsCell = tableView.dequeueReusableCellWithIdentifier(StoreCredentialsCell)as? SwitchCell
if(storeCredentialsCell!= nil){
...
NSLog(将代理设置为%@ for%@,self.description,storeCredentialsCell.description)
storeCredentialsCell !.delegate = self
...
}
日志输出是正如预期的那样,当它与代理的实际设置匹配时,应用程序会崩溃与
EXC_BAD_ACCESS(code = 1,address = 0xfffffffffffffff8) p>
我还应该注意,如果在委托?.switchChanged(self,state:swtSelector.on)触发时不设置委托值它也会导致EXC_BAD_ACCESS错误,但是根据代理的doco,如果委托没有设置任何内容,那么这个应用程序将无法正常执行。
========== =================
我已经简化为一个基本项目来复制问题。
TestTableViewController.swift
import UIKit
class TestTableViewController:UITableViewController,TestCellDelegate {
init(style:UITableViewStyle){
super.init(style:style)
}
init(coder aDecoder:NSCoder!){
super.init(coder:aDecoder)
}
覆盖func viewDidLoad(){
super .viewDidLoad()
}
覆盖func didReceiveMemoryWarning(){
super.didReceiveMemoryWarning()
}
覆盖func numberOfSectionsInTableView(tableView :UITableView?) - > int {
return 1
}
覆盖func tableView(tableView:UITableView?,numberOfRowsInSection部分:Int) - > int {
return 1
}
覆盖func tableView(tableView:UITableView?,cellForRowAtIndexPath indexPath:NSIndexPath?) - > UITableViewCell? {
let cell = tableView!.dequeueReusableCellWithIdentifier(Cell,forIndexPath:indexPath)as? TestCell
if(cell!= nil){
cell!.delegate = self
cell!.lblTest.text =Test Successful
}
返回单元格
}
func eventFired(发件人:TestCell){
NSLog(Hooray!)
}
TestCell.swift
导入UIKit
协议TestCellDelegate {
func eventFired(sender:TestCell)
}
class TestCell:UITableViewCell {
@IBOutlet var lblTest:UILabel
@IBOutlet var swtTest:UISwitch
var delegate:TestCellDelegate?
init(style:UITableViewCellStyle,reuseIdentifier:String){
super.init(style:style,reuseIdentifier:reuseIdentifier)
}
@IBAction func switchChanged(sender:UISwitch){
delegate?.eventFired(self)
}
}
然后我创建了一个具有TestTableViewController类的表视图控制器场景。表视图是动态的,具有TestCell类型的单个单元格。该单元格包含一个标签和一个与TestCell类的IBOutlets绑定的开关。 switchChanged函数绑定到交换机上的值更改事件。
相同的EXC_BAD_ACCESS错误被抛出。
目前,如果委托应该是Objective-C类的对象,那么您必须使用 @objc
显式标记协议(像UITableViewController):
@objc协议SwiftProtocol
这将实现与Objective-C
的互操作
I'm going through and learning Swift by porting an existing application. I'm stuck on setting a delegate and cannot work out what the issue is.
I have a class which extends UITableViewCell
import UIKit
protocol SwitchCellDelegate{
func switchChanged(switchCell: SwitchCell, state: Bool)
}
class SwitchCell: UITableViewCell {
@IBOutlet var swtSelector: UISwitch
@IBOutlet var lblTitle: UILabel
var delegate: SwitchCellDelegate?
init(style: UITableViewCellStyle, reuseIdentifier: String) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
}
@IBAction func switchChanged(){
delegate?.switchChanged(self, state: swtSelector.on)
}
}
Then in the ViewController is defined as
class SettingsViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, SwitchCellDelegate {
and within the method
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
we have
case 2:
storeCredentialsCell = tableView.dequeueReusableCellWithIdentifier("StoreCredentialsCell") as? SwitchCell
if(storeCredentialsCell != nil){
...
NSLog("Setting delegate to %@ for %@", self.description, storeCredentialsCell.description)
storeCredentialsCell!.delegate = self
...
}
the log output is as expected but when it hits the actual setting of the delegate the app crashes with
EXC_BAD_ACCESS(code=1, address=0xfffffffffffffff8)
I should also note that if I don't set the delegate value when delegate?.switchChanged(self, state: swtSelector.on) fires it also causes an EXC_BAD_ACCESS error but according to the doco for delegates this should fail gracefully if delegate is not set to anything.
===========================
I've simplified down to a basic project to replicate the issue.
TestTableViewController.swift
import UIKit
class TestTableViewController: UITableViewController, TestCellDelegate {
init(style: UITableViewStyle) {
super.init(style: style)
}
init(coder aDecoder: NSCoder!) {
super.init(coder: aDecoder)
}
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func numberOfSectionsInTableView(tableView: UITableView?) -> Int {
return 1
}
override func tableView(tableView: UITableView?, numberOfRowsInSection section: Int) -> Int {
return 1
}
override func tableView(tableView: UITableView?, cellForRowAtIndexPath indexPath: NSIndexPath?) -> UITableViewCell? {
let cell = tableView!.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as? TestCell
if(cell != nil){
cell!.delegate = self
cell!.lblTest.text = "Test Successful"
}
return cell
}
func eventFired(sender: TestCell) {
NSLog("Hooray!")
}
TestCell.swift
import UIKit
protocol TestCellDelegate{
func eventFired(sender: TestCell)
}
class TestCell: UITableViewCell {
@IBOutlet var lblTest: UILabel
@IBOutlet var swtTest: UISwitch
var delegate: TestCellDelegate?
init(style: UITableViewCellStyle, reuseIdentifier: String) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
}
@IBAction func switchChanged(sender: UISwitch){
delegate?.eventFired(self)
}
}
I then created a single Table View Controller Scene with Class of TestTableViewController. The table view is dynamic with a single cell of type TestCell. That cell contains one label and one switch which are bound to the IBOutlets from the TestCell class. The switchChanged function is bound to the value changed event on the switch.
Same EXC_BAD_ACCESS error is thrown.
Currently you have to explicitly mark your protocols with @objc
if the delegate should be an Object of a Objective-C class (Like the UITableViewController):
@objc protocol SwiftProtocol
This will enable interoperating with Objective-C
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