ios - 从 'AUAudioUnitBus?' 转换为无关类型 'UICollectionViewLayoutAttribute' 总是失败 - swift 2 iOS 9

Question

我正在尝试修复另一个错误

Ambiguous use of 'subscript'

我得到模糊下标错误的旧代码是这样的:

override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> (UICollectionViewLayoutAttributes!) {
    return self.itemAttributes[indexPath.section][indexPath.row] as! UICollectionViewLayoutAttributes
  }

我得到不相关类型转换的新代码是这样的:

  override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> (UICollectionViewLayoutAttributes!) {
    if let result: UICollectionViewLayoutAttributes = self.itemAttributes?[indexPath.section][indexPath.row] as? UICollectionViewLayoutAttributes {
      return result
    }else {
      return nil
    }
    //return self.itemAttributes[indexPath.section][indexPath.row] as! UICollectionViewLayoutAttributes
  }

这是完整的类代码:

import UIKit

class CustomCollectionViewLayout: UICollectionViewLayout {

  var numberOfColumns = 7 // the number of columns
  var itemAttributes : NSMutableArray!
  var itemsSize : NSMutableArray!
  var contentSize : CGSize!

  func setColumnNumber(columnNum: Int) {
    numberOfColumns = columnNum
  }

  override func prepareLayout() {
    if self.collectionView?.numberOfSections() == 0 {
      return
    }

    if (self.itemAttributes != nil && self.itemAttributes.count > 0) {
      for section in 0..<self.collectionView!.numberOfSections() {
        let numberOfItems : Int = self.collectionView!.numberOfItemsInSection(section)
        for index in 0..<numberOfItems {
          if section != 0 && index != 0 {
            continue
          }

          let attributes : UICollectionViewLayoutAttributes = self.layoutAttributesForItemAtIndexPath(NSIndexPath(forItem: index, inSection: section))
          if section == 0 {
            var frame = attributes.frame
            frame.origin.y = self.collectionView!.contentOffset.y
            attributes.frame = frame
          }

          if index == 0 {
            var frame = attributes.frame
            frame.origin.x = self.collectionView!.contentOffset.x
            attributes.frame = frame
          }
        }
      }
      return
    }

    if (self.itemsSize == nil || self.itemsSize.count != numberOfColumns) {
      self.calculateItemsSize()
    }

    var column = 0
    var xOffset : CGFloat = 0
    var yOffset : CGFloat = 0
    var contentWidth : CGFloat = 0
    var contentHeight : CGFloat = 0

    for section in 0..<self.collectionView!.numberOfSections() {
      let sectionAttributes = NSMutableArray()

      for index in 0..<numberOfColumns {
        let itemSize = self.itemsSize[index].CGSizeValue()
        let indexPath = NSIndexPath(forItem: index, inSection: section)
        let attributes = UICollectionViewLayoutAttributes(forCellWithIndexPath: indexPath)
        attributes.frame = CGRectIntegral(CGRectMake(xOffset, yOffset, itemSize.width, itemSize.height))

        if section == 0 && index == 0 {
          attributes.zIndex = 1024;
        } else  if section == 0 || index == 0 {
          attributes.zIndex = 1023
        }

        if section == 0 {
          var frame = attributes.frame
          frame.origin.y = self.collectionView!.contentOffset.y
          attributes.frame = frame
        }
        if index == 0 {
          var frame = attributes.frame
          frame.origin.x = self.collectionView!.contentOffset.x
          attributes.frame = frame
        }

        sectionAttributes.addObject(attributes)

        xOffset += itemSize.width
        column++

        if column == numberOfColumns {
          if xOffset > contentWidth {
            contentWidth = xOffset
          }

          column = 0
          xOffset = 0
          yOffset += itemSize.height
        }
      }
      if (self.itemAttributes == nil) {
        self.itemAttributes = NSMutableArray(capacity: self.collectionView!.numberOfSections())
      }
      self.itemAttributes .addObject(sectionAttributes)
    }

    let attributes : UICollectionViewLayoutAttributes = self.itemAttributes.lastObject?.lastObject as! UICollectionViewLayoutAttributes
    contentHeight = attributes.frame.origin.y + attributes.frame.size.height
    if( contentWidth == 0 || contentHeight == 0){return;}
    self.contentSize = CGSizeMake(contentWidth, contentHeight)
  }

  override func collectionViewContentSize() -> CGSize {
    if( self.contentSize != nil){
      return self.contentSize
    }else {
      return CGSizeMake(0, 0)
    }
  }

  override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> (UICollectionViewLayoutAttributes!) {
    if let result: UICollectionViewLayoutAttributes = self.itemAttributes?[indexPath.section][indexPath.row] as? UICollectionViewLayoutAttributes {
      return result
    }else {
      return nil
    }
    //return self.itemAttributes[indexPath.section][indexPath.row] as! UICollectionViewLayoutAttributes
  }

  override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
    var attributes = [UICollectionViewLayoutAttributes]()
    if self.itemAttributes != nil {
      for section in self.itemAttributes {

        let filteredArray  =  section.filteredArrayUsingPredicate(

          NSPredicate(block: { (evaluatedObject, bindings) -> Bool in
            return CGRectIntersectsRect(rect, evaluatedObject.frame)
          })
          ) as! [UICollectionViewLayoutAttributes]


        attributes.appendContentsOf(filteredArray)

      }
    }

    return attributes
  }

  override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
    return true
  }

  func sizeForItemWithColumnIndex(columnIndex: Int) -> CGSize {
    let text : String = "25.10.15"
//    switch (columnIndex) {
//    case 0:
//      text = "Col 0"
//    case 1:
//      text = "Col 1"
//    case 2:
//      text = "Col 2"
//    case 3:
//      text = "Col 3"
//    case 4:
//      text = "Col 4"
//    case 5:
//      text = "Col 5"
//    case 6:
//      text = "Col 6"
//    default:
//      text = "Col 7"
//    }

    let size : CGSize = (text as NSString).sizeWithAttributes([NSFontAttributeName: UIFont.systemFontOfSize(17.0)])
    let width : CGFloat = size.width + 25
    return CGSizeMake(width, 30)
  }

  func calculateItemsSize() {
    self.itemsSize = NSMutableArray(capacity: numberOfColumns)
    for index in 0..<numberOfColumns {
      self.itemsSize.addObject(NSValue(CGSize: self.sizeForItemWithColumnIndex(index)))
    }
  }
}

Answer 1

错误没有多大意义，但我建议使用 Swift 数据类型而不是“NS”数据类型。

尝试将您的 NSMutableArray! 声明替换为:

var itemAttributes = [[UICollectionViewLayoutAttributes]]()

这为您提供了一个可以使用 [m][n] 索引访问的数组。

例子:

var itemAttributes = [[UICollectionViewLayoutAttributes]]()
var attrList = [UICollectionViewLayoutAttributes]()
let oneAttr = UICollectionViewLayoutAttributes()
attrList.append(oneAttr)

itemAttributes.append(attrList)

let attr = itemAttributes[0][0]