ios 数据类型转换 UIImage转换为NSData NSData转换为NSString

1.UIImage转换为NSData

NSData *data;
if (UIImagePNGRepresentation(image) == nil) {

            data = UIImageJPEGRepresentation(image, 1);

        } else {

            data = UIImagePNGRepresentation(image);
}

2.NSData转换为NSString

NSString *str=[[NSString alloc]initWithData:data];