我有一个UIImageView，允许用户放置并保存图像，直到可以保存。问题是，我无法弄清楚如何实际保存和检索我放置在视图中的图像。
我检索并将图像放在UIImageView中，如下所示：
//Get Image
- (void) getPicture:(id)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = (sender == myPic) ? UIImagePickerControllerSourceTypeCamera : UIImagePickerControllerSourceTypeSavedPhotosAlbum;
[self presentModalViewController:picker animated:YES];
[picker release];
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage (UIImage *)image editingInfo:(NSDictionary *)editingInfo {
myPic.image = image;
[picker dismissModalViewControllerAnimated:YES];
}
它在我的UIImageView中显示所选图像就好了，但我不知道如何保存它。我正在Core Data中保存视图的所有其他部分（主要是UITextfield）。我搜索并搜索过，并尝试过人们建议的许多代码，但要么我没有正确输入代码，要么这些建议与我设置代码的方式无关。这可能是前者。我想使用相同的操作（保存按钮）将图像保存在UIImageView中我用来保存UITextFields中的文本。这是我如何保存我的UITextField信息：
// Handle Save Button
- (void)save {
// Get Info From UI
[self.referringObject setValue:self.myInfo.text forKey:@"myInfo"];
就像我之前说的那样，我已经尝试了几种方法来实现这一点，但无法掌握它。在我生命中我第一次想要对无生命的物体造成身体伤害，但我已经设法克制自己。
我希望能够将用户放置在应用程序文档文件夹中的UIImageView中的图像保存，然后能够检索它并将其放在另一个UIImageView中，以便在用户将该视图推入堆栈时显示。非常感谢任何帮助！
答案 0 :(得分：333)
一切都很好，伙计。不要伤害自己或他人。
您可能不希望将这些图像存储在Core Data中，因为如果数据集变得太大，这会影响性能。最好将图像写入文件。
NSData *pngData = UIImagePNGRepresentation(image);
这会拉出您捕获的图像的PNG数据。从这里，您可以将其写入文件：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0]; //Get the docs directory
NSString *filePath = [documentsPath stringByAppendingPathComponent:@"image.png"]; //Add the file name
[pngData writeToFile:filePath atomically:YES]; //Write the file
稍后阅读它会以同样的方式工作。像上面那样建立路径，然后：
NSData *pngData = [NSData dataWithContentsOfFile:filePath];
UIImage *image = [UIImage imageWithData:pngData];
你可能想要做的是创建一个为你创建路径字符串的方法，因为你不希望那些代码遍布各处。它可能看起来像这样：
- (NSString *)documentsPathForFileName:(NSString *)name
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
return [documentsPath stringByAppendingPathComponent:name];
}
希望这有帮助。
答案 1 :(得分：3)
let documentDirectoryPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString
let img = UIImage(named: "1.jpg")!// Or use whatever way to get the UIImage object
let imgPath = URL(fileURLWithPath: documentDirectoryPath.appendingPathComponent("1.jpg"))// Change extension if you want to save as PNG
do{
try UIImageJPEGRepresentation(img, 1.0)?.write(to: imgPath, options: .atomic)//Use UIImagePNGRepresentation if you want to save as PNG
}catch let error{
print(error.localizedDescription)
}
答案 2 :(得分：1)
对于Swift 4.2，这是Fangming Ning's answer ，使用recommended and more Swifty method进行更新，以便检索文档目录路径并提供更好的文档。也为方明宁提供了新的方法。
guard let documentDirectoryPath = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else {
return
}
//Using force unwrapping here because we're sure "1.jpg" exists. Remember, this is just an example.
let img = UIImage(named: "1.jpg")!
// Change extension if you want to save as PNG.
let imgPath = documentDirectoryPath.appendingPathComponent("1.jpg")
do {
//Use .pngData() if you want to save as PNG.
//.atomic is just an example here, check out other writing options as well. (see the link under this example)
//(atomic writes data to a temporary file first and sending that file to its final destination)
try img.jpegData(compressionQuality: 1)?.write(to: imgPath, options: .atomic)
} catch {
print(error.localizedDescription)
}
答案 3 :(得分：0)
在斯威夫特：
let paths: [NSString?] = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .LocalDomainMask, true)
if let path = paths[0]?.stringByAppendingPathComponent(imageName) {
do {
try UIImagePNGRepresentation(image)?.writeToFile(path, options: .DataWritingAtomic)
} catch {
return
}
}
答案 4 :(得分：0)
#pragma mark == Save Image To Local Directory
-(void)saveImageToDocumentDirectoryWithImage: (UIImage *)capturedImage {
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents folder
NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"/images"];
//Create a folder inside Document Directory
if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
[[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error]; //Create folder
NSString *imageName = [NSString stringWithFormat:@"%@/img_%@.png", dataPath, [self getRandomNumber]] ;
// save the file
if ([[NSFileManager defaultManager] fileExistsAtPath:imageName]) {
// delete if exist
[[NSFileManager defaultManager] removeItemAtPath:imageName error:nil];
}
NSData *imageDate = [NSData dataWithData:UIImagePNGRepresentation(capturedImage)];
[imageDate writeToFile: imageName atomically: YES];
}
#pragma mark
#pragma mark == Generate Random Number
-(NSString *)getRandomNumber{
NSTimeInterval time = ([[NSDate date] timeIntervalSince1970]); // returned as a double
long digits = (long)time; // this is the first 10 digits
int decimalDigits = (int)(fmod(time, 1) * 1000); // this will get the 3 missing digits
//long timestamp = (digits * 1000) + decimalDigits;
NSString *timestampString = [NSString stringWithFormat:@"%ld%d",digits ,decimalDigits];
return timestampString;
}
答案 5 :(得分：-1)
Swift 4 with extension
extension UIImage{
func saveImage(inDir:FileManager.SearchPathDirectory,name:String){
guard let documentDirectoryPath = FileManager.default.urls(for: inDir, in: .userDomainMask).first else {
return
}
let img = UIImage(named: "\(name).jpg")!
// Change extension if you want to save as PNG.
let imgPath = URL(fileURLWithPath: documentDirectoryPath.appendingPathComponent("\(name).jpg").absoluteString)
do {
try UIImageJPEGRepresentation(img, 0.5)?.write(to: imgPath, options: .atomic)
} catch {
print(error.localizedDescription)
}
}
}
用法示例
image.saveImage(inDir: .documentDirectory, name: "pic")