如何在运行时正确压缩UIImages [英] How To Properly Compress UIImages At Runtime

问题描述

我需要加载4张图片进行同步编辑。当我从用户库加载它们时，内存超过500mb并崩溃。

I need to load 4 images for simultaneous editing. When I load them from the users library, the memory exceeds 500mb and crashes.

在我进行任何压缩尝试之前，这是来自原始分配转储的日志：

Here is a log from a raw allocations dump before I did any compression attempts:

代码：

var pickedImage = UIImage(data: imageData)

工具：

我已经阅读了几篇关于压缩UIImages的帖子。我试过减少UIImage：

I have read several posts on compressing UIImages. I have tried reducing the UIImage:

新代码：

var pickedImage = UIImage(data: imageData, scale:0.1)

乐器：

减少UIImage的比例没有影响？！非常奇怪。

Reducing the scale of the UIImage had NO EFFECT?! Very odd.

所以现在我尝试基于完整的UIImage创建JPEG压缩

So now I tried creating a JPEG compression based on the full UIImage

新代码：

var pickedImage = UIImage(data: imageData)
var compressedData:NSData = UIImageJPEGRepresentation(pickedImage,0)
var compressedImage:UIImage = UIImage(data: compressedData)!//this is now used to display

工具：

现在，我怀疑是因为我正在转换它仍在加载的图像。由于这一切都发生在来自PHImageManager的回调中，我需要一种方法从NSData创建一个压缩的UIImage，但是将比例设置为0.1没有做到。

Now, I suspect because I am converting the image its still being loaded. And since this is all occuring inside a callback from PHImageManager, I need a way to create a compressed UIImage from the NSData, but the setting the scale to 0.1 did NOTHING.

所以关于如何从NSData压缩这个UIImage的任何建议都会挽救生命!!!

So any suggestions as to how I can compress this UIImage right from the NSData would be life saving!!!

谢谢

推荐答案

在处理图像之前，我最终硬编码了尺寸缩小。下面是代码：

I ended up hard coding a size reduction before processing the image. Here is the code:

PHImageManager.defaultManager().requestImageForAsset(asset, targetSize:CGSizeMake(CGFloat(asset.pixelWidth), CGFloat(asset.pixelHeight)), contentMode: .AspectFill, options: options)
                {
                    result, info in
                    var minRatio:CGFloat = 1
                    //Reduce file size so take 1/2 UIScreen.mainScreen().bounds.width/2 || CGFloat(asset.pixelHeight) > UIScreen.mainScreen().bounds.height/2)
                    {
                        minRatio = min((UIScreen.mainScreen().bounds.width/2)/(CGFloat(asset.pixelWidth)), ((UIScreen.mainScreen().bounds.height/2)/CGFloat(asset.pixelHeight)))
                    }
                    var size:CGSize = CGSizeMake((CGFloat(asset.pixelWidth)*minRatio),(CGFloat(asset.pixelHeight)*minRatio))
                    UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
                    result.drawInRect(CGRectMake(0, 0, size.width, size.height))
                    var final = UIGraphicsGetImageFromCurrentImageContext()
                    var image = iImage(uiimage: final)
                }

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