xcode5：如何保存和加载图像？

Question

I'm developing an app, where I can apply filters on an image.
I want to create an undo button which resets the original image in the imageView .
The solution is that I just save the original image in it's own UIImage object before I apply any filters to it. This way I can just go back to that in my undo method.

Does somebody know how I can do this?

Answer 1

Take a look at the docs here: https://developer.apple.com/library/ios/documentation/uikit/reference/UIKitFunctionReference/Reference/reference.html

You can do what you want with UIImagePNGRepresentation() .

Then to re-read: imageWithContentsOfFile:

Answer 2

Get Image from disk . Suppose image stored in document directory .

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectory = [paths objectAtIndex:0];

NSString *yourImgPath = [documentsDirectory stringByAppendingPathComponent:@"1.png"];

UIImage *originalImage = [UIImage imageWithContentsOfFile:yourImgPath];

Create tempImage from originalImage

UIImage *tempImage = originalImage;

Appy filters on tempImage

EDIT : How to save then below is method to save in document directory .

- (BOOL)saveImageInDocDir:(UIImage *)image withImagename:(NSString *)strImgName {
  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString *documentsDirectory = [paths objectAtIndex:0];
  NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:strImgName];
  NSData *imageData = UIImagePNGRepresentation(image);
  BOOL isSaved = [imageData writeToFile:savedImagePath atomically:YES];   
  return isSaved;
}

You can also use NSTempraryDirectory to save images as its safe from cloud backup