xcode 无法分配给属性：“self”是不可变的
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Cannot assign to property: 'self' is immutable
提问by grahamcracker1234
I am creating a page view application. I have written code for the ViewController:
我正在创建一个页面视图应用程序。我已经为 ViewController 编写了代码：
import UIKit
class ViewController: UIViewController {
var pageViewController : UIPageViewController!
var pageTitles : NSArray!
var pageImages : NSArray!
@IBAction func restartAction(sender: AnyObject) {}
override func viewDidLoad() {
super.viewDidLoad()
self.pageTitles = NSArray(objects: "This Is Page One!", "This Is Page Two!")
self.pageImages = NSArray(objects: "page1", "page2")
self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
self.pageViewController.dataSource = self // <–– Error
let startVC = self.viewControllerAtIndex(0) as ContentViewController
let viewControllers = NSArray(object: startVC)
self.pageViewController.setViewControllers(viewControllers as? [UIViewController], direction: .Forward, animated: true, completion: nil)
self.pageViewController.view.frame = CGRectMake(0, 30, self.view.frame.width, self.view.frame.height - 60)
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func viewControllerAtIndex(index: Int) -> ContentViewController {
if ((self.pageTitles.count == 0) || (index >= self.pageTitles.count)) {
return ContentViewController()
}
let vc : ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController
vc.imageFile = self.pageImages[index] as! String
vc.titleText = self.pageTitles[index] as! String
vc.pageIndex = index
return vc
}
func pageViewController(pageViewController: UIPageViewController, viewcontrollerBeforeViewController viewController: UIViewController) ->UIViewController? {
let vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if index == 0 || index == NSNotFound {
return nil
}
index--
return self.viewControllerAtIndex(index)
}
func pageViewController(pageViewController: UIPageViewController, viewcontrollerAfterViewController viewController: UIViewController) ->UIViewController? {
let vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if index == NSNotFound {
return nil
}
index++
if index == self.pageTitles.count {
return nil
}
return self.viewControllerAtIndex(index)
}
}
But I am getting an error on this line self.pageViewController.dataSource = self. The error is:
但是我在这条线上遇到了一个错误self.pageViewController.dataSource = self。错误是：
Cannot assign to property: 'self' is immutable
无法分配给属性：“self”是不可变的
I am unsure of why self is immutable and how to fix it. If someone could please help, thanks in advance.
我不确定为什么 self 是不可变的以及如何修复它。如果有人可以帮忙，请提前致谢。
采纳答案by Leslie Godwin
In swift you'll need to call self.pageViewController.setDelegate(self)
在 swift 你需要打电话 self.pageViewController.setDelegate(self)
Delegates have been declared as methods, not properties in some cases
在某些情况下，委托已被声明为方法，而不是属性
回答by Dave Roberts
I think the compiler is not being very helpful here - try declaring the controller as following datasource protocol and see if that fixes this odd error
我认为编译器在这里不是很有帮助 - 尝试将控制器声明为以下数据源协议，看看是否可以解决这个奇怪的错误
class ViewController: UIViewController, UIPageViewControllerDataSource { etc
