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.o
      objc-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.o
      objc-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

这里有更详细的解决办法：
解决symbol(s) not found for architecture arm64报错（2）