NSData和UIImage相互转化

/NSData转换为UIImage

NSData *imageData = [NSData dataWithContentsOfFile:imagePath];

UIImage *image = [UIImage imageWithData:imageData];

//UIImage转换为NSData

//第二个参数为压缩倍数

NSData *imageData = UIImageJPEGRepresentation(image,1.0f);