如何在swift中调用c函数“TIFFGetField”。有没有人有想法或给我sample？谢谢//ThefunctiondeclaredexternintTIFFGetField(TIFF*tif,uint32tag,...);/*sample:inobjective-cisworkingverywell*/unsignedintwidth;TIFFGetField(tiff,TIFFTAG_IMAGEWIDTH,&width);/*sample:inswiftfailed*/varwidth:UInt32=0TIFFGetField(tiff,uint32(TIFFTAG_IMAG