1、An unknown error occurred.
如果仅仅提示“An unknown error occurred.” 而没有别的提示，很有可能是设备内存已满，没有足够的空间来安装这个应用。
2、BSXPCMessage received error for message: Connection interrupted
我在图片识别，生成CIImage 时报出此东警告。
通过设置 CIContext 的options 可以消除此警告---不过，过滤器的效率好像会变慢一点
1 NSData *imageData = UIImageJPEGRepresentation(image, 1); 2 3 // kCIContextUseSoftwareRenderer : 软件渲染 -- 可以消除 "BSXPCMessage received error for message: Connection interrupted" 警告 4 // kCIContextPriorityRequestLow : 低优先级在 GPU 渲染-- 设置为false可以加快图片处理速度 5 CIContext *context = [CIContext contextWithOptions:@{kCIContextUseSoftwareRenderer : @(true), kCIContextPriorityRequestLow : @(false)}]; 6 7 CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:context options:nil]; 8 CIImage *ciImage = [CIImage imageWithData:imageData]; 9 10 NSArray *ar = [detector featuresInImage:ciImage]; 11 CIQRCodeFeature *feature = [ar firstObject]; 12 NSLog(@"context: %@", feature.messageString);
3、“(null)” is of a model that is not supported by this version of Xcode. Please use a different device.
重启 Xcode 就好
4、证书错误，先重装下这个证书，点此下载。
5、ARC forbids Objective-C objects in struct
在ARC环境下，结构体中要有oc对象，必须用 __unsafe_unretained 修饰；
typedef struct PBUser__storage_ {
uint32_t _has_storage_[1];
__unsafe_unretained NSString *userId;
__unsafe_unretained NSString *nick;
__unsafe_unretained NSString *avatar;
__unsafe_unretained NSString *password;
__unsafe_unretained NSString *email;
__unsafe_unretained NSString *mobile;
__unsafe_unretained NSString *qqOpenId;
__unsafe_unretained NSString *sinaId;
__unsafe_unretained NSString *weixinId;
} PBUser__storage_;
6、The operation couldn’t be completed. (LaunchServicesError error 0.)
重置模拟器，或者 clean。