我最终尝试将url rep形式的字典中的照片数组转换为base64以通过json发送。
这是字典代码和日志：
NSDictionary *dict = [self.form dictionaryWithValuesForKeys:keys];
NSLog(@"dict::%@",dict);
的NSLog：
dict::{
boardLodgingFurnished = "<null>";
caption = "<null>";
cars = "";
photos = (
{
caption = "";
urlRep = "assets-library://asset/asset.JPG?id=CE8A426B-3B59-4172-8761-CC477F3BB3EE&ext=JPG";
},
{
caption = "";
urlRep = "assets-library://asset/asset.JPG?id=F4B68A42-1CA0-4880-9FB5-177CB091A28C&ext=JPG";
}
);
yearsAtLocation = "";
yearsInTheBusiness = "";
}
因此，对于字典中的每张照片，我想取urlRep并将其转换为base64字符串，并在字典中将urlRep替换为它。
我现在拥有的......不确定我是否朝着正确的方向前进：
for (id imageURL in [dict objectForKey:@"photos"])
{
ALAssetsLibrary *library = [ALAssetsLibrary new];
ALAsset *ourAsset = [self assetForURL:imageURL withLibrary:library];
/* Check out ALAssets */
NSLog(@"%@", ourAsset);
ALAssetRepresentation *representation = [ourAsset defaultRepresentation];
CGImageRef imageRef = [representation fullResolutionImage];
//TODO: Deal with JPG or PNG
NSData *imageData = UIImageJPEGRepresentation([UIImage imageWithCGImage:imageRef], 0.1);
NSLog(@"imagedata??%@", [imageData base64EncodedString]);
//need to know how to add this back to dict
}
从上面调用以下方法，但在
的while循环中崩溃-[__NSDictionaryI scheme]: unrecognized selector sent to instance 0x166dd090
2014-01-03 10:57:27.361 Inspection App[2728:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryI scheme]: unrecognized selector sent to instance 0x166dd090'
方法
- (ALAsset *)assetForURL:(NSURL *)url withLibrary:(ALAssetsLibrary *)assetsLibrary {
__block ALAsset *result = nil;
__block NSError *assetError = nil;
dispatch_semaphore_t sema = dispatch_semaphore_create(0);
[assetsLibrary assetForURL:url resultBlock:^(ALAsset *asset) {
result = asset;
dispatch_semaphore_signal(sema);
} failureBlock:^(NSError *error) {
assetError = error;
dispatch_semaphore_signal(sema);
}];
if ([NSThread isMainThread]) {
while (!result && !assetError) {
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}
}
else {
dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
}
return result;
}
修改
if (photoUrls.count) {
for (id photos in photoUrls){
NSString *urlString = photos;
[self base64ImageAtUrlString:urlString result:^(NSString *base64) {
NSLog(@"imagedata??%@", base64);
}];
}
}
else {
NSLog(@"where are my urls?");
}
NSMutableDictionary *jsonWithPhotos = [dict mutableCopy];
[jsonWithPhotos setObject:convertedImages forKey:@"photo64"];
NSLog(@"jjson photos::%@", jsonWithPhotos);
更新方法
- (void)base64ImageAtUrlString:(NSString *)urlString result:(void (^)(NSString *))completion {
NSURL *url = [NSURL URLWithString:urlString];
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library assetForURL:url resultBlock:^(ALAsset *asset) {
// borrowing your code, here... didn't check it....
ALAssetRepresentation *representation = [asset defaultRepresentation];
CGImageRef imageRef = [representation fullResolutionImage];
//TODO: Deal with JPG or PNG
NSData *imageData = UIImageJPEGRepresentation([UIImage imageWithCGImage:imageRef], 0.1);
NSString *base64 = [imageData base64EncodedString];
completion(base64);
[convertedImages addObject:base64];
// NSLog(@"converted::%@",convertedImages);
} failureBlock:^(NSError *error) {
NSLog(@"that didn't work %@", error);
}];
}
当我记录jsonWithPhotos时，对象photo64只是一个空白数组
答案 0 :(得分：2)
崩溃是由于关于字典的代码中的错误假设。鉴于已解析为json的字典的已发布描述，您需要获取这样的URL：
// collect the photo urls in an array
NSMutableArray *photoUrls = [NSMutableArray array];
// photos is an array of dictionaries in the dictionary
NSArray *photos = dict[@"photos"];
for (NSDictionary *photo in photos) {
// photo is a dictionary containing a "caption" and a "urlRep"
[photoUrls addObject:photo[@"urlRep"]];
}
现在，您可以继续使用其作业只是转换的方法。您的问题可能包含更多有关如何执行此操作的问题。我建议开始简单。看看你是否可以进行一次转换。通过反向写入来测试它，从base64返回到图像。
编辑0 ：如果不深入检查，我会重新构建您的编码尝试，如下所示：
- (void)base64ImageAtUrlString:(NSString *)urlString result:(void (^)(NSString *))completion {
NSURL *url = [NSURL URLWithString:urlString];
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library assetForURL:url resultBlock:^(ALAsset *asset) {
// borrowing your code, here... didn't check it....
ALAssetRepresentation *representation = [asset defaultRepresentation];
CGImageRef imageRef = [representation fullResolutionImage];
//TODO: Deal with JPG or PNG
NSData *imageData = UIImageJPEGRepresentation([UIImage imageWithCGImage:imageRef], 0.1);
NSString *base64 = [imageData base64EncodedString];
completion(base64);
} failureBlock:^(NSError *error) {
NSLog(@"that didn't work %@", error);
}];
}
这样称呼：
if (photoUrls.count) {
NSString *urlString = photoUrls[0];
[self base64ImageAtUrlString:urlString result:^(NSString *base64) {
NSLog(@"imagedata??%@", base64);
}];
} else {
NSLog(@"where are my urls?");
}
一旦它正常工作，看看你是否可以逆转它，从base64数据中创建一个图像。最后，一旦完成所有工作，您就可以处理潜在的内存问题。我的建议是考虑一次编码一个，一次一个地发送到服务器并释放它们之间的所有内容。
编辑1 - 每个后续问题，如果你想用base64编码替换url数组中的所有url，它可能会像这样（记住这可能会占用大量内存） ）：
- (void)base64ImagesAtUrls:(NSMutableArray *)urls result:(void (^)(void))completion {
__block NSInteger completed = 0; // this is how we'll know that we're done
// this approach doesn't depend on the asset library retrievals completing
// sequentially, even though they probably will
for (int i=0; i<urls.count; i++) {
NSString *urlString = urls[i];
[self base64ImageAtUrlString:urlString result:^(NSString *base64) {
[urls replaceObjectAtIndex:i withObject:base64];
if (++completed == urls.count) completion();
}];
}
}