從iOS資產庫加載圖像

Question

我正在使用以下代碼從assetlibrary加載圖像。 它無法正常工作，如果我單擊displayImage uiimageviewer，它會顯示無效的訪問嘗試，超過了它自己的ALAssetsLibrary的生存期。

頭文件

#import <UIKit/UIKit.h>
#import "BFCropInterface.h"
#import "GRKImage.h"
#import <AssetsLibrary/AssetsLibrary.h>

@interface BFViewController : UIViewController{
    GRKImage *gImg;
}

@property (nonatomic, strong) IBOutlet UIImageView *displayImage;
@property (nonatomic, strong) UIImage *originalImage;
@property (nonatomic, strong) BFCropInterface *cropper;
@property (nonatomic, retain) GRKImage *gImg;
@property (strong, atomic) ALAssetsLibrary* library;

- (IBAction)cropPressed:(id)sender;
- (IBAction)originalPressed:(id)sender;
- (IBAction)savePressed:(id)sender;



@end

主文件：viewDidload內部

if ( [[self.gImg.URL absoluteString] hasPrefix:@"assets-library://"] ){


    typedef void (^ALAssetsLibraryAssetForURLResultBlock)(ALAsset *asset);
    typedef void (^ALAssetsLibraryAccessFailureBlock)(NSError *error);

    ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset){

        ALAssetRepresentation *rep = [myasset defaultRepresentation];
        CGImageRef iref = [rep fullResolutionImage];
        float scale=[rep scale];
        ALAssetOrientation orientation=[rep orientation];
        if (iref){

            dispatch_async(dispatch_get_main_queue(), ^{
                UIImage *originalImage = [UIImage imageWithCGImage:iref scale:scale orientation:(UIImageOrientation)orientation];

                self.displayImage.contentMode = UIViewContentModeScaleAspectFit;

                [self.displayImage setImage:originalImage];

            });


        }
    };

    ALAssetsLibraryAccessFailureBlock failureblock  = ^(NSError *myerror){

        //failed to get image.
    };

    self.library = [[ALAssetsLibrary alloc] init];
    [self.library assetForURL:self.gImg.URL resultBlock:resultblock failureBlock:failureblock];
     }

Answer 1

您當前正在嘗試在主線程上使用ALAssetRepresentation rep ，此時將釋放assetslibrary 。 嘗試將assetslibrary作為屬性存儲在類中，或者在庫仍然有效時將scale和orientation assetslibrary塊。

---

如果只顯示它，則也不需要使用fullResolutionImage 。 請改用fullScreenImage 。