相对于帧宽度和宽高比的动态UICollectionViewCell宽度 [英] Dynamic UICollectionViewCell width with respect to frame width and aspect ratio

问题描述

这是来自 UICollectionViewCell 4.4和5.5英寸的动态调整大小

虽然该解决方案非常棒，但我想生成一个动态数量的项目基于设备的宽度，宽高比以及我必须显示的总项目数量，UIVIewController内的单元格（kCellsPerRow）。我不知道如何计算kCellsPerRow的正确数量，以便一旦达到宽高比限制，它们就不会调整大小。

While that solution is great, I'd like to generate a dynamic amount of item cells (kCellsPerRow) within the UIVIewController based on the device's width, aspect ratio, and amount of total items I have to display. I just can't figure out how to calculate the right amount of kCellsPerRow so that they are not too resized once they hit an aspect ratio limit.

这是我所拥有的far：

Here's what I have so far:

var kCellsPerRow = ceil(global.TotalAmount)                //Total Amount of Cells
var windowWidth = layout.collectionView!.frame.width        // Device's Window Width 
var dynamicWidth = windowWidth / CGFloat(kCellsPerRow)    // Current Width of Each Cell
var dynamicHeight = windowWidth / CGFloat(kCellsPerRow)    // Current Height of Each Cell
var limit = (Double(dynamicWidth) / Double(windowWidth))*(9/2) < (2/9)    // Constraint/Threshold

if ( limit ) {
    var newkCellsPerRow = CGFloat(kCellsPerRow * (2/9))    // Attempt
    newkCellsPerRow = 9  // Fixed Size of 9 but what if we can dynamically figure out the perfect number such that its not so tiny!

    dynamicWidth = layout.collectionView!.frame.width / newkCellsPerRow
    dynamicHeight = layout.collectionView!.frame.width / newkCellsPerRow
}

// Create Cell
layout.itemSize = CGSize(width: dynamicWidth, height: dynamicHeight)

推荐答案

您需要指定的是单元格应该是最小的尺寸。细胞至少与该大小一样宽（高），并且可能更大。

All you need to specify is the smallest size a cell should be. Cells will be at least as wide (and high) as that size, and possibly larger.

方法：

这是一个方法，将根据其collectionView的宽度来计算适当的单元格大小：

Here's a method which will calculate the appropriate cell size based on the width of its collectionView:

// These variables are set in the Storyboard, but shown here for clarity
flowLayout.minimumInteritemSpacing = 10
flowLayout.sectionInset = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)

let minimumSize: CGFloat = 90.0 // A cell's width or height won't ever be smaller than this

func cellWidthForViewWidth(viewWidth: CGFloat) -> CGFloat {
    // Determine the largest number of cells that could possibly fit in a row, based on the cell's minimum size
    var numberOfCellsPerRow = Int(viewWidth / minimumSize)

    // Adjust for interitem spacing and section insets
    let availableWidth = viewWidth - flowLayout.sectionInset.left - flowLayout.sectionInset.right - flowLayout.minimumInteritemSpacing * CGFloat(numberOfCellsPerRow - 1)
    numberOfCellsPerRow = Int(availableWidth / minimumSize)

    return availableWidth / CGFloat(numberOfCellsPerRow) // Make this an integral width if desired
}

处理非1：1宽高比

如果您的宽高比与1不同：1，您可以通过将计算出的宽度除以纵横比来简单地确定动态高度。

If your aspect ratio happened to be different from 1:1, you would simply determine the dynamic height by dividing the calculated width by the aspect ratio.

let aspectRatio: CGFloat = 3.0/2.0
let cellWidth = cellWidthForViewWidth(CGRectGetWidth(collectionView.frame))
let cellHeight = cellWidth / aspectRatio

设置项目尺寸：

由于您的宽高比为1：1，我们只需要计算单元格的宽度，然后将该值用于宽度和高度

Since your aspect ratio is 1:1, we only need to calculate the width for a cell, then use that value for both width and height.

根据计算的动态大小设置实际项目大小：

Set the actual item size based on the calculated dynamic size:

let actualCellSize = cellWidthForViewWidth(CGRectGetWidth(collectionView.frame))
flowLayout.itemSize = CGSize(width: actualCellSize, height: actualCellSize)

示例结果

这将让您了解单元格的大小，基于在各种容器宽度上：

This will give you an idea what size a cell would be, based on various container widths:

print(cellWidthForViewWidth(320.0))  //  93,  3 cells per row
print(cellWidthForViewWidth(400.0))  // 116,  3 cells per row
print(cellWidthForViewWidth(640.0))  //  93,  6 cells per row
print(cellWidthForViewWidth(800.0))  // 101,  7 cells per row
print(cellWidthForViewWidth(1024.0)) //  90, 10 cells per row

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