优化asset选中后获取大图的方法，使其request可取消

TZImagePickerController/TZImagePickerController/TZAssetCell.m

@@ -76,7 +76,9 @@
     }
     // 如果用户选中了该图片，提前获取一下大图
     if (model.isSelected) {
-        [self fetchBigImage];
+        [self requestBigImage];
+    } else {
+        [self cancelBigImageRequest];
     }
     if (model.needOscillatoryAnimation) {
         [UIView showOscillatoryAnimationWithLayer:self.selectImageView.layer type:TZOscillatoryAnimationToBigger];
@@ -141,12 +143,9 @@
             [UIView showOscillatoryAnimationWithLayer:_selectImageView.layer type:TZOscillatoryAnimationToBigger];
         }
         // 用户选中了该图片，提前获取一下大图
-        [self fetchBigImage];
+        [self requestBigImage];
     } else { // 取消选中，取消大图的获取
-        if (_bigImageRequestID && _progressView) {
-            [[PHImageManager defaultManager] cancelImageRequest:_bigImageRequestID];
-            [self hideProgressView];
-        }
+        [self cancelBigImageRequest];
     }
 }
 
@@ -155,13 +154,13 @@
     self.imageView.alpha = 1.0;
 }
 
-- (void)fetchBigImage {
-    _bigImageRequestID = [[TZImageManager manager] getPhotoWithAsset:_model.asset completion:^(UIImage *photo, NSDictionary *info, BOOL isDegraded) {
-        if (self->_progressView) {
+- (void)requestBigImage {
+    _bigImageRequestID = [[TZImageManager manager] requestImageDataForAsset:_model.asset completion:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
+        if (self.progressView) {
             [self hideProgressView];
         }
     } progressHandler:^(double progress, NSError *error, BOOL *stop, NSDictionary *info) {
-        if (self->_model.isSelected) {
+        if (self.model.isSelected) {
             progress = progress > 0.02 ? progress : 0.02;;
             self.progressView.progress = progress;
             self.progressView.hidden = NO;
@@ -172,8 +171,18 @@
         } else {
             *stop = YES;
             [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
+            [self cancelBigImageRequest];
         }
-    } networkAccessAllowed:YES];
+    }];
+}
+
+- (void)cancelBigImageRequest {
+    if (_bigImageRequestID) {
+        [[PHImageManager defaultManager] cancelImageRequest:_bigImageRequestID];
+    }
+    if (_progressView) {
+        [self hideProgressView];
+    }
 }
 
 #pragma mark - Lazy load

TZImagePickerController/TZImagePickerController/TZImageManager.h

@@ -65,6 +65,7 @@
 - (int32_t)getPhotoWithAsset:(id)asset photoWidth:(CGFloat)photoWidth completion:(void (^)(UIImage *photo,NSDictionary *info,BOOL isDegraded))completion;
 - (int32_t)getPhotoWithAsset:(id)asset completion:(void (^)(UIImage *photo,NSDictionary *info,BOOL isDegraded))completion progressHandler:(void (^)(double progress, NSError *error, BOOL *stop, NSDictionary *info))progressHandler networkAccessAllowed:(BOOL)networkAccessAllowed;
 - (int32_t)getPhotoWithAsset:(id)asset photoWidth:(CGFloat)photoWidth completion:(void (^)(UIImage *photo,NSDictionary *info,BOOL isDegraded))completion progressHandler:(void (^)(double progress, NSError *error, BOOL *stop, NSDictionary *info))progressHandler networkAccessAllowed:(BOOL)networkAccessAllowed;
+- (int32_t)requestImageDataForAsset:(id)asset completion:(void (^)(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info))completion progressHandler:(void (^)(double progress, NSError *error, BOOL *stop, NSDictionary *info))progressHandler;
 
 /// Get full Image 获取原图
 /// 如下两个方法completion一般会调多次，一般会先返回缩略图，再返回原图(详见方法内部使用的系统API的说明)，如果info[PHImageResultIsDegradedKey] 为 YES，则表明当前返回的是缩略图，否则是原图。

TZImagePickerController/TZImagePickerController/TZImageManager.m

@@ -474,6 +474,36 @@ static dispatch_once_t onceToken;
     return [self getPhotoWithAsset:asset photoWidth:fullScreenWidth completion:completion progressHandler:progressHandler networkAccessAllowed:networkAccessAllowed];
 }
 
+- (int32_t)requestImageDataForAsset:(id)asset completion:(void (^)(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info))completion progressHandler:(void (^)(double progress, NSError *error, BOOL *stop, NSDictionary *info))progressHandler {
+    if ([asset isKindOfClass:[PHAsset class]]) {
+        PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
+        options.progressHandler = ^(double progress, NSError *error, BOOL *stop, NSDictionary *info) {
+            dispatch_async(dispatch_get_main_queue(), ^{
+                if (progressHandler) {
+                    progressHandler(progress, error, stop, info);
+                }
+            });
+        };
+        options.networkAccessAllowed = YES;
+        options.resizeMode = PHImageRequestOptionsResizeModeFast;
+        int32_t imageRequestID = [[PHImageManager defaultManager] requestImageDataForAsset:asset options:options resultHandler:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
+            if (completion) completion(imageData,dataUTI,orientation,info);
+        }];
+        return imageRequestID;
+    } else if ([asset isKindOfClass:[ALAsset class]]) {
+        ALAsset *alAsset = (ALAsset *)asset;
+        dispatch_async(dispatch_get_global_queue(0,0), ^{
+            ALAssetRepresentation *assetRep = [alAsset defaultRepresentation];
+            CGImageRef fullScrennImageRef = [assetRep fullScreenImage];
+            UIImage *fullScrennImage = [UIImage imageWithCGImage:fullScrennImageRef scale:2.0 orientation:UIImageOrientationUp];
+            dispatch_async(dispatch_get_main_queue(), ^{
+                if (completion) completion(UIImageJPEGRepresentation(fullScrennImage, 0.83), nil, UIImageOrientationUp, nil);
+            });
+        });
+    }
+    return 0;
+}
+
 - (int32_t)getPhotoWithAsset:(id)asset photoWidth:(CGFloat)photoWidth completion:(void (^)(UIImage *photo,NSDictionary *info,BOOL isDegraded))completion progressHandler:(void (^)(double progress, NSError *error, BOOL *stop, NSDictionary *info))progressHandler networkAccessAllowed:(BOOL)networkAccessAllowed {
     if ([asset isKindOfClass:[PHAsset class]]) {
         CGSize imageSize;