将UIImage转换为NSData并返回UIImage
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我必须从数据库中填充表格单元格,并且图像在设备上。我要将这个图像存储在imageDataObject
中,如何将UIImage
转换为NSData
。请建议,我尝试了很多解决方案,但它没有将NSData
转换回UIImage
。
cell.textLabel.text = [[offlineImageListArray objectAtIndex:indexPath.row] imageName];
UIImage *thumbnail = [self retrieveImageFromDevice:[[offlineImageListArray objectAtIndex:indexPath.row] imageName]];
NSData* data = ??????????;
ImageData *imageDataObject = [[ImageData alloc] initWithImageId:[[offlineImageListArray objectAtIndex:indexPath.row]imageId]
imageName:[[offlineImageListArray objectAtIndex:indexPath.row] imageName] imageData:data];
[imagesArray addObject:imageDataObject];
要将UIImage
转换为NSData
,请使用UIImageJPEGRepresentation(UIImage *image, CGFloat compressionQuality)
或UIImagePNGRepresentation(UIImage *image)
要将NSData
转换为UIImage
,请使用[UIImage imageWithData:imageData]
所以你的例子看起来像这样:
cell.textLabel.text = [[offlineImageListArray objectAtIndex:indexPath.row] imageName];
UIImage *thumbnail = [self retrieveImageFromDevice:[[offlineImageListArray objectAtIndex:indexPath.row] imageName]];
NSData* data = UIImagePNGRepresentation(thumbnail);
ImageData *imageDataObject = [[ImageData alloc] initWithImageId:[[offlineImageListArray objectAtIndex:indexPath.row]imageId] imageName:[[offlineImageListArray objectAtIndex:indexPath.row] imageName] imageData:data];
[imagesArray addObject:imageDataObject];
参考文献:https://developer.apple.com/LIBRARY/IOS/documentation/UIKit/Reference/UIKitFunctionReference/Reference/reference.html https://developer.apple.com/Library/ios/documentation/UIKit/Reference/UIImage_Class/Reference/Reference.html
试试这个:
用它来将UIImage
转换为NSData
。
NSData *imagedata = UIImagePNGRepresentation(thumbnail);
尝试将图像数据转换回UIImage
UIImage *image= [UIImage imageWithData:imagedata];
在Swift版本中:
let imageData = UIImagePNGRepresentation(image!)!
let imageFromData = UIImage(data: imageData)
使用if-let阻止数据以防止应用程序崩溃和安全执行代码,因为函数UIImagePNGRepresentation返回一个可选值。
if let img = UIImage(named: "TestImage.png") {
if let data:Data = UIImagePNGRepresentation(img) {
// Handle operations with data here...
}
}
注意:数据是Swift 3类。在Swift 3中使用Data而不是NSData
通用图像操作(如png和jpg):
if let img = UIImage(named: "TestImage.png") { //UIImage(named: "TestImage.jpg")
if let data:Data = UIImagePNGRepresentation(img) {
handleOperationWithData(data: data)
} else if let data:Data = UIImageJPEGRepresentation(img, 1.0) {
handleOperationWithData(data: data)
}
}
*******
func handleOperationWithData(data: Data) {
// Handle operations with data here...
if let image = UIImage(data: data) {
// Use image...
}
}
通过使用扩展名:
extension UIImage {
var pngRepresentationData: Data? {
return UIImagePNGRepresentation(img)
}
var jpegRepresentationData: Data? {
return UIImageJPEGRepresentation(self, 1.0)
}
}
*******
if let img = UIImage(named: "TestImage.png") { //UIImage(named: "TestImage.jpg")
if let data = img.pngRepresentationData {
handleOperationWithData(data: data)
} else if let data = img.jpegRepresentationData {
handleOperationWithData(data: data)
}
}
*******
func handleOperationWithData(data: Data) {
// Handle operations with data here...
if let image = UIImage(data: data) {
// Use image...
}
}
从图像转换数据:
请尝试JPEG或PNG表示,具体取决于您的图像格式:
UIImageJPEGRepresentation
以JPEG格式返回指定图像的数据。
NSData * UIImageJPEGRepresentation (
UIImage *image,
CGFloat compressionQuality
);
UIImagePNGRepresentation
以PNG格式返回指定图像的数据
NSData * UIImagePNGRepresentation (
UIImage *image
);
例:
extension UIImage {
var pngRepresentationData: Data? {
return UIImagePNGRepresentation(img)
}
var jpegRepresentationData: Data? {
return UIImageJPEGRepresentation(self, 1.0)
}
}
使用:
let data = myImage.jpegRepresentationData
let data1 = myImage.pngRepresentationData
从数据转换图像:
let image = UIImage(data: data)
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