Since iOS8, unable to load image properties such as EXIF - ios8

Question

My code was working great on iOS7.x. But since I compile for iOS 8, it does no longer retrieve others information than basic ones. Here is the only information I get now (no more DateTime, Artist, Model etc.):
{
ColorModel = RGB;
DPIHeight = 72;
DPIWidth = 72;
Depth = 8;
Orientation = 1;
PixelHeight = 2448;
PixelWidth = 3264;
"{Exif}" = {
ColorSpace = 1;
PixelXDimension = 3264;
PixelYDimension = 2448;
};
"{JFIF}" = {
DensityUnit = 1;
JFIFVersion = (
1,
0,
1
);
XDensity = 72;
YDensity = 72;
};
"{TIFF}" = {
Orientation = 1;
};
}
My code is as follows:
-(NSDictionary*)getExif:(NSURL*)assetURL asset:(ALAssetRepresentation *)image_representation {
// create a buffer to hold image data
uint8_t *buffer = (Byte*)malloc(image_representation.size);
NSUInteger length = [image_representation getBytes:buffer fromOffset: 0.0 length:image_representation.size error:nil];
if (length != 0) {
// buffer -> NSData object; free buffer afterwards
NSData *adata = [[NSData alloc] initWithBytesNoCopy:buffer length:image_representation.size freeWhenDone:YES];
// identify image type (jpeg, png, RAW file, ...) using UTI hint
NSDictionary* sourceOptionsDict = [NSDictionary dictionaryWithObjectsAndKeys:(id)[image_representation UTI],kCGImageSourceTypeIdentifierHint,nil];
// create CGImageSource with NSData
CGImageSourceRef sourceRef = CGImageSourceCreateWithData((__bridge CFDataRef) adata,
(__bridge CFDictionaryRef) sourceOptionsDict);
// get imagePropertiesDictionary
CFDictionaryRef imagePropertiesDictionary = CGImageSourceCopyPropertiesAtIndex(sourceRef,0, NULL);
NSLog(#"image props: %#",imagePropertiesDictionary);
CFDictionaryRef propsRef = (CFDictionaryRef)CFDictionaryGetValue(imagePropertiesDictionary, #"{TIFF}");
NSDictionary *props = (__bridge NSDictionary*)propsRef;
NSMutableDictionary *d = [[NSMutableDictionary alloc] init];
NSString * make = nil;
NSString *model = nil;
NSString *
s = [props objectForKey:#"DateTime" ]; if (s) [d setObject: s forKey:#"DateTime"];
s = [props objectForKey:#"Artist" ]; if (s) [d setObject:[s capitalizedString] forKey:#"Artist"];
s = make = [props objectForKey:#"Make" ]; if (s) [d setObject:s forKey:#"Make"];
s = model = [props objectForKey:#"Model" ]; if (s) {
if (make ) s = [s stringByReplacingOccurrencesOfString:make withString:#""];
[d setObject:s forKey:#"Model"];
}
// etc.

Answer 1

IOS8. Photos application bug?
I think it's a bug of Photos.Framework .Because I can get fully metadata when fetch all PHAssets,but lost some information when I fetch the PHAsset by collection.