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如何获取iPhone拍摄的png照片的拍摄时间,位置信息等图片属性?png格式中可以存储一些辅助信息（ancillary information)
这个特性可用来在图像文件中存储一些文本注释信息。
独立于计算机软硬件环境。
使用无损压缩。
PNG文件格式中要增加下列GIF文件格式所没有 的特性：
每个像素为48位的真彩色图像。
每个像素为16位的灰度图像。
可为灰度图和真彩色图添加α通道。
添加图像的γ信息。
使用循环冗余码（cyclic redundancy code，CRC）检测损害的文件。
加快图像显示的逐次逼近显示方式。
标准的读/写工具包。
但是现在有png格式的照片,我如何从照片中读取拍摄时间和位置信息等图片的属性呢?
还有在拍照的时候需要程序中写代码将这些信息写入到照片中吗? |
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| dengyanjun | 2012-05-23 15:31 | 可以吗可以吗可以吗，求～～
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| ad4621 | 2012-06-05 16:10 | - (void) imagePickerController: (UIImagePickerController *) picker didFinishPickingMediaWithInfo: (NSDictionary *) info {
//给照片添加GPS信息并保存到相册
if(picker.sourceType == UIImagePickerControllerSourceTypeCamera)
{
//图片
UIImage *image= [info objectForKey:UIImagePickerControllerOriginalImage];
//元数据
NSDictionary *dict = [info objectForKey:UIImagePickerControllerMediaMetadata];
NSMutableDictionary *metadata=[NSMutableDictionary dictionaryWithDictionary:dict];
//EXIF数据
NSMutableDictionary *EXIFDictionary =[[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary]mutableCopy];
//GPS数据
NSMutableDictionary *GPSDictionary = [[metadata objectForKey:(NSString *)kCGImagePropertyGPSDictionary]mutableCopy];
if(!EXIFDictionary) {
EXIFDictionary = [NSMutableDictionary dictionary];
[EXIFDictionary setValue:@"xml_user_comment" forKey:(NSString *)kCGImagePropertyExifUserComment];
[metadata setObject:EXIFDictionary forKey:(NSString *)kCGImagePropertyExifDictionary];
}
if(!GPSDictionary) {
/* 请使用CLLocationManager 获取当前拍照的GPS信息*/
// 使用CLLocationManager获取当前位置的CLLocation对象
CLLocation *location=....;
//将CLLocation对象转化为如下格式的NSDictionary
NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:@"UTC"];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setTimeZone:timeZone];
[formatter setDateFormat:@"HH:mm:ss.SS"];
NSDictionary *gpsDict = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithFloat:fabs(location.coordinate.latitude)], kCGImagePropertyGPSLatitude,
((location.coordinate.latitude >= 0) ? @"N" : @"S"), kCGImagePropertyGPSLatitudeRef,
[NSNumber numberWithFloat:fabs(location.coordinate.longitude)], kCGImagePropertyGPSLongitude,
((location.coordinate.longitude >= 0) ? @"E" : @"W"), kCGImagePropertyGPSLongitudeRef,
[formatter stringFromDate:[location times*****p]], kCGImagePropertyGPSTimeS*****p,
nil];
//将GPS数据写入图片并保存到相册
if (info && [info objectForKey:UIImagePickerControllerMediaMetadata] && gpsDict) {
[[info objectForKey:UIImagePickerControllerMediaMetadata] setValue:gpsDict forKey:(NSString*)kCGImagePropertyGPSDictionary];
}
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
ALAssetsLibraryWriteImageCompletionBlock imageWriteCompletionBlock =
^(NSURL *newURL, NSError *error) {
if (error) {
NSLog( @"Error writing image with metadata to Photo Library: %@", error );
} else {
NSLog( @"Wrote image with metadata to Photo Library");
}
};
//保存相片到相册 注意:必须使用[image CGImage]不能使用强制转换: (__bridge CGImageRef)image,否则保存照片将会报错
[library writeImageToSavedPhotosAlbum:[image CGImage]
metadata:metadata
completionBlock:imageWriteCompletionBlock];
}
}
//从相册中选择一张照片获取它的GPS信息
else if(picker.sourceType == UIImagePickerControllerSourceTypePhotoLibrary){
__block UIImage *image= [info objectForKey:UIImagePickerControllerOriginalImage];
self.siteImg=image;
__block NSMutableDictionary *imageMetadata = nil;
NSURL *assetURL = [info objectForKey:UIImagePickerControllerReferenceURL];
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library assetForURL:assetURL
resultBlock:^(ALAsset *asset) {
imageMetadata = [[NSMutableDictionary alloc] initWithDictionary:asset.defaultRepresentation.metadata];
NSDictionary *GPSDict=[imageMetadata objectForKey:(NSString*)kCGImagePropertyGPSDictionary];
/* GPSDict 里面即是照片的GPS信息,具体可以输出看看*/
}
failureBlock:^(NSError *error) {
}];
}
[picker dismissModalViewControllerAnimated: YES];
} |
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