Swift学习笔记四

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Project 10 Names to Faces

  1. 把 collection view 直接拖拽到 view controller，它就能自动占满整个空间。
  2. collection view cell 的背景默认为透明，可以改为白色（错误的选成了imageView,导致显示不正常）

  3. 把collectionView的DataSource、Delegate设置为ViewController，需要conform协议

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    class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
      func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
         return people.count
    }

     func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
       let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Person", forIndexPath: indexPath) as! PersonCell
       return cell
     }

  4. 使用UIImagePickerController必须同时遵守 UIImagePickerControllerDelegate, UINavigationControllerDelegate协议。

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    func addNewPerson() {
      let picker = UIImagePickerController()
      picker.allowsEditing = true
      picker.delegate = self
      presentViewController(picker, animated: true, completion: nil)
    }

    func imagePickerControllerDidCancel(picker: UIImagePickerController) {
      dismissViewControllerAnimated(true, completion: nil)
    }

    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
      var newImage: UIImage

      if let possibleImage = info["UIImagePickerControllerEditedImage"] as? UIImage {
        newImage = possibleImage
      } else if let possibleImage = info["UIImagePickerControllerOriginalImage"] as? UIImage {
        newImage = possibleImage
      } else {
        return
      }

      let imageName = NSUUID().UUIDString
      let imagePath = getDocumentsDirectory().stringByAppendingPathComponent(imageName)

      if let jpegData = UIImageJPEGRepresentation(newImage, 80) {
        jpegData.writeToFile(imagePath, atomically: true)
      }

      dismissViewControllerAnimated(true, completion: nil)
    }

  5. 得到文件的路径

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    func getDocumentsDirectory() -> NSString {
      let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
      let documentsDirectory = paths[0]
      return documentsDirectory
    }

  6. String! and String? 可以为nil, 但是 String 必须有 value。

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    var name: String
    init(name: String, image: String) {
    self.name = name
    self.image = image //can only mean one thing: assign the parameter to the class's property.
    }

  7. 使用reloadData()方法更新数据。

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    var people = [Person]()
    let person = Person(name: "Unknown", image: imageName)
    people.append(person)
    collectionView.reloadData()

  8. 设计cell的边界颜色、宽度、圆角

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    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
      let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Person", forIndexPath: indexPath) as! PersonCell

      let person = people[indexPath.item]

      cell.name.text = person.name

      let path = getDocumentsDirectory().stringByAppendingPathComponent(person.image)
      cell.imageView.image = UIImage(contentsOfFile: path)
      cell.imageView.layer.borderColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.3).CGColor
      cell.imageView.layer.borderWidth = 2
      cell.imageView.layer.cornerRadius = 3
      cell.layer.cornerRadius = 7

      return cell
    }

  9. 在UIAlertController里传值，使用addTextFieldWithConfigurationHandler(nil)方法。

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    func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
      let person = people[indexPath.item]

      let ac = UIAlertController(title: "Rename person", message: nil, preferredStyle: .Alert)
      ac.addTextFieldWithConfigurationHandler(nil)

      ac.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil))
      ac.addAction(UIAlertAction(title: "OK", style: .Default) { [unowned self, ac] _ in
        let newName = ac.textFields![0]
        person.name = newName.text!

        self.collectionView.reloadData()
      })

      presentViewController(ac, animated: true, completion: nil)
    }

  10. 使用照相机
    UIImagePickerController.isSourceTypeAvailable(.Camera)