今天在引入一个第三方的拍照选择照片的库时，编译报错。

Undefined symbols for architecture x86_64:"_ALAssetPropertyAssetURL", referenced from:-[TZImageManager getAssetIdentifier:] in TZImageManager.o"_ALAssetPropertyDuration", referenced from:___90-[TZImageManager getAssetsFromFetchResult:allowPickingVideo:allowPickingImage:completion:]_block_invoke139 in TZImageManager.o___97-[TZImageManager getAssetFromFetchResult:atIndex:allowPickingVideo:allowPickingImage:completion:]_block_invoke in TZImageManager.o"_ALAssetPropertyType", referenced from:___90-[TZImageManager getAssetsFromFetchResult:allowPickingVideo:allowPickingImage:completion:]_block_invoke139 in TZImageManager.o___97-[TZImageManager getAssetFromFetchResult:atIndex:allowPickingVideo:allowPickingImage:completion:]_block_invoke in TZImageManager.o"_ALAssetPropertyURLs", referenced from:-[TZImageManager getVideoWithAsset:completion:] in TZImageManager.o-[TZImageManager isAssetsArray:containAsset:] in TZImageManager.o"_ALAssetTypeVideo", referenced from:___90-[TZImageManager getAssetsFromFetchResult:allowPickingVideo:allowPickingImage:completion:]_block_invoke139 in TZImageManager.o___97-[TZImageManager getAssetFromFetchResult:atIndex:allowPickingVideo:allowPickingImage:completion:]_block_invoke in TZImageManager.o"_ALAssetsGroupPropertyName", referenced from:___66-[TZImageManager getCameraRollAlbum:allowPickingImage:completion:]_block_invoke in TZImageManager.o___60-[TZImageManager getAllAlbums:allowPickingImage:completion:]_block_invoke in TZImageManager.o"_OBJC_CLASS_$_ALAsset", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_ALAssetsFilter", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_ALAssetsGroup", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_ALAssetsLibrary", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAsset", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAssetCollection", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAssetCreationRequest", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAssetResourceCreationOptions", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHCachingImageManager", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHFetchOptions", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHFetchResult", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHImageManager", referenced from:objc-class-ref in TZAssetCell.oobjc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHImageRequestOptions", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHPhotoLibrary", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHVideoRequestOptions", referenced from:objc-class-ref in TZImageManager.o"_PHImageCancelledKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o___55-[TZImageManager getOriginalPhotoWithAsset:completion:]_block_invoke in TZImageManager.o"_PHImageErrorKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o___55-[TZImageManager getOriginalPhotoWithAsset:completion:]_block_invoke in TZImageManager.o"_PHImageManagerMaximumSize", referenced from:-[TZImageManager getOriginalPhotoWithAsset:completion:] in TZImageManager.o"_PHImageResultIsDegradedKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke_2 in TZImageManager.o"_PHImageResultIsInCloudKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

经过几个小时的查资料，和尝试，基本上确定了是由于部分依赖的框架没有导入（天知道为什么会没有导入，我在另一个项目里面直接拖进去就可以编译的，坑爹的xcode）。
于是我仔细看了下报错的内容，都是指向TZImageManager，于是我到对应的.m文件里面，发现它引用了系统的AssetsLibrary框架：

屏幕快照 2016-07-01 16.41.07.png

我尝试手动导入这个框架:

屏幕快照 2016-07-01 16.45.05.png

编译一下，原来报27个错，现在只有17个了，看来有效果。于是我继续找还缺少了什么框架。现在的报错如下：

Undefined symbols for architecture x86_64:"_OBJC_CLASS_$_PHAsset", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAssetCollection", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAssetCreationRequest", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHAssetResourceCreationOptions", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHCachingImageManager", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHFetchOptions", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHFetchResult", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHImageManager", referenced from:objc-class-ref in TZAssetCell.oobjc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHImageRequestOptions", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHPhotoLibrary", referenced from:objc-class-ref in TZImageManager.o"_OBJC_CLASS_$_PHVideoRequestOptions", referenced from:objc-class-ref in TZImageManager.o"_PHImageCancelledKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o___55-[TZImageManager getOriginalPhotoWithAsset:completion:]_block_invoke in TZImageManager.o"_PHImageErrorKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o___55-[TZImageManager getOriginalPhotoWithAsset:completion:]_block_invoke in TZImageManager.o"_PHImageManagerMaximumSize", referenced from:-[TZImageManager getOriginalPhotoWithAsset:completion:] in TZImageManager.o"_PHImageResultIsDegradedKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke_2 in TZImageManager.o"_PHImageResultIsInCloudKey", referenced from:___58-[TZImageManager getPhotoWithAsset:photoWidth:completion:]_block_invoke in TZImageManager.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

当时在看这个报错的时候，一头雾水，PHxxx的库根本找不到，于是在.m里面找，半天之后猜是不是Photos框架，导入了之后编译成功！
猜得很艰辛啊。
现在写这个文章的时候，突然发现对应的TZImageManager.h文件里果然导入了Photos框架……

屏幕快照 2016-07-01 16.53.18.png

猜得那么辛苦，原来.h里面就有答案，醉了。
解决这个问题花了一个下午的时间，写一篇文章做个备份，免得下次又被坑。