react-native报错[NSTaggedPointerString unsignedIntValue]: unrecognized selector sent to instance的解决办法

Xcode运行React-Native新建的项目会在

NSUInteger headersContentLength = headers[@"Content-Length"] != nil ? [headers[@"Content-Length"] unsignedIntValue] : 0;

这里报错，报错信息是

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSTaggedPointerString unsignedIntValue]: unrecognized selector sent to instance 

解决办法是将这句改为

NSUInteger headersContentLength = headers[@"Content-Length"] != nil ? (NSUInteger)[headers[@"Content-Length"] integerValue] : 0;

完美解决