微信分享蚀瘸、微博分享等等骚勘，對(duì)圖片大小有要求猾编，所以需要壓縮桥爽，把該方法放到Extension+UIImage即可
// 圖片壓縮
func compressImage(maxLength: Int) -> UIImage {
let tempMaxLength: Int = maxLength / 8
var compression: CGFloat = 1
guard var data = UIImageJPEGRepresentation(self, compression) where data.length > tempMaxLength else { return self }
// 壓縮大小
var max: CGFloat = 1
var min: CGFloat = 0
for _ in 0..<6 {
compression = (max + min) / 2
data = UIImageJPEGRepresentation(self, compression)!
if CGFloat(data.length) < CGFloat(tempMaxLength) * 0.9 {
min = compression
} else if data.length > tempMaxLength {
max = compression
} else {
break
}
}
var resultImage: UIImage = UIImage(data: data)!
if data.length < tempMaxLength { return resultImage }
// 壓縮大小
var lastDataLength: Int = 0
while data.length > tempMaxLength && data.length != lastDataLength {
lastDataLength = data.length
let ratio: CGFloat = CGFloat(tempMaxLength) / CGFloat(data.length)
print("Ratio =", ratio)
let size: CGSize = CGSize(width: Int(resultImage.size.width * sqrt(ratio)),
height: Int(resultImage.size.height * sqrt(ratio)))
UIGraphicsBeginImageContext(size)
resultImage.drawInRect(CGRect(x: 0, y: 0, width: size.width, height: size.height))
resultImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
data = UIImageJPEGRepresentation(resultImage, compression)!
}
return resultImage
}
