【发布时间】：2016-06-12 07:39:50
【问题描述】：
我正在制作一个在 UIImageView 中显示 gif 的应用程序，该应用程序从解析加载 gif。我偶然发现的问题是，每当我加载 Gif 时，它都会使用大约 20 mb 的内存，并且在我执行 segue 时没有分配这个内存。我从 UIImageView 中删除了图像本身，但它仍然没有释放内存。
这是我用来显示 gif 的代码：
extension UIImage {
public class func gifWithData(data: NSData) -> UIImage? {
guard let source = CGImageSourceCreateWithData(data, nil) else {
print("SwiftGif: Source for the image does not exist")
return nil
}
return UIImage.animatedImageWithSource(source)
}
public class func gifWithName(name: String) -> UIImage? {
guard let bundleURL = NSBundle.mainBundle().URLForResource(name, withExtension: "gif") else {
print("SwiftGif: This image named \"\(name)\" does not exist")
return nil
}
guard let imageData = NSData(contentsOfURL: bundleURL) else {
print("SwiftGif: Cannot turn image named \"\(name)\" into NSData")
return nil
}
return gifWithData(imageData)
}
class func delayForImageAtIndex(index: Int, source: CGImageSource!) -> Double {
var delay = 0.1
// Get dictionaries
let cfProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil)
let gifProperties: CFDictionaryRef = unsafeBitCast(
CFDictionaryGetValue(cfProperties,
unsafeAddressOf(kCGImagePropertyGIFDictionary)),
CFDictionary.self)
// Get delay time
var delayObject: AnyObject = unsafeBitCast(
CFDictionaryGetValue(gifProperties,
unsafeAddressOf(kCGImagePropertyGIFUnclampedDelayTime)),
AnyObject.self)
if delayObject.doubleValue == 0 {
delayObject = unsafeBitCast(CFDictionaryGetValue(gifProperties,
unsafeAddressOf(kCGImagePropertyGIFDelayTime)), AnyObject.self)
}
delay = delayObject as! Double
if delay < 0.1 {
delay = 0.1 // Make sure they're not too fast
}
return delay
}
class func gcdForPair(var a: Int?, var _ b: Int?) -> Int {
// Check if one of them is nil
if b == nil || a == nil {
if b != nil {
return b!
} else if a != nil {
return a!
} else {
return 0
}
}
// Swap for modulo
if a < b {
let c = a
a = b
b = c
}
// Get greatest common divisor
var rest: Int
while true {
rest = a! % b!
if rest == 0 {
return b! // Found it
} else {
a = b
b = rest
}
}
}
class func gcdForArray(array: Array<Int>) -> Int {
if array.isEmpty {
return 1
}
var gcd = array[0]
for val in array {
gcd = UIImage.gcdForPair(val, gcd)
}
return gcd
}
class func animatedImageWithSource(source: CGImageSource) -> UIImage? {
let count = CGImageSourceGetCount(source)
var images = [CGImageRef]()
var delays = [Int]()
// Fill arrays
for i in 0..<count {
// Add image
if let image = CGImageSourceCreateImageAtIndex(source, i, nil) {
images.append(image)
}
// At it's delay in cs
let delaySeconds = UIImage.delayForImageAtIndex(Int(i),
source: source)
delays.append(Int(delaySeconds * 1000.0)) // Seconds to ms
}
// Calculate full duration
let duration: Int = {
var sum = 0
for val: Int in delays {
sum += val
}
return sum
}()
// Get frames
let gcd = gcdForArray(delays)
var frames = [UIImage]()
var frame: UIImage
var frameCount: Int
for i in 0..<count {
frame = UIImage(CGImage: images[Int(i)])
frameCount = Int(delays[Int(i)] / gcd)
for _ in 0..<frameCount {
frames.append(frame)
}
}
// Heyhey
let animation = UIImage.animatedImageWithImages(frames,
duration: Double(duration) / 1000.0)
return animation
}
class func FinalFrame(source: CGImageSource) -> UIImage? {
let count = CGImageSourceGetCount(source)
var images = [CGImageRef]()
var delays = [Int]()
var finalFrame = UIImage()
// Fill arrays
for i in 0..<count {
// Add image
if let image = CGImageSourceCreateImageAtIndex(source, i, nil) {
images.append(image)
}
// At it's delay in cs
let delaySeconds = UIImage.delayForImageAtIndex(Int(i),
source: source)
delays.append(Int(delaySeconds * 1000.0)) // Seconds to ms
}
// Get frames
let gcd = gcdForArray(delays)
var frames = [UIImage]()
var frame: UIImage
var frameCount: Int
for i in 0..<count {
frame = UIImage(CGImage: images[Int(i)])
frameCount = Int(delays[Int(i)] / gcd)
for _ in 0..<frameCount {
frames.append(frame)
}
}
finalFrame = frames[frames.count-1]
return finalFrame
}
}
这可能是我遇到内存问题的原因吗？ 感谢任何帮助！
【问题讨论】：
-
GIF 和 APNG 都可以处理低内存请求，如下所示：stackoverflow.com/a/25478854/763355