iOS开发笔记-26:图片上传

        //图片压缩
            NSData *data;
            if (UIImagePNGRepresentation(HeadImage) == nil) {
                data = UIImageJPEGRepresentation(HeadImage, 1);
            } else {
                data = UIImagePNGRepresentation(HeadImage);
            }
            CGFloat how = data.length / 1000 ;
            JJLog(@"how = %fKB\n",how);
            //比例
            NSInteger scale = how > 500 ? 500 / how : 1.0;
            //压缩图片，图片上传不能大于500kb
            data = UIImageJPEGRepresentation(HeadImage, scale);

//文件流形式上传图片
        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        formatter.dateFormat = @"yyyyMMddHHmmss";
        NSString *str = [formatter stringFromDate:[NSDate date]];
        NSString *fileName = [NSString stringWithFormat:@"%@.jpg", str];
        // 上传图片，以文件流的格式
        [formData appendPartWithFileData:data name:@"file" fileName:fileName mimeType:@"image/jpg"];

//以字符串，参数的形式上传图片，这个时候一半都是需要对数据进行base64编码，后台一般接受图片也要进行base64解析
NSString *imageString = [data base64EncodedStringWithOptions:0];