问题描述
大家好，
我想一劳永逸地澄清一下有关通过BackgroundFileTransfer通过蜂窝数据连接下载大文件的局限性.
I would like to have a clarification once and for all regarding the limitations of downloading large files over cellular data connection with BackgroundFileTransfer.
文档仍然指出限制为20MB.但是，Internet上已经有谣言说它已经增加到50MB.我也曾在自己的应用程序中看到50MB的下载量，但这似乎非常随机.
The docs still state that the limitation is 20MB. But there has been rumors on the Internet that is has been increases to 50MB. I have also seen 50MB downloads working in my own app, but it seems very random.
有人可以澄清一下吗?谢谢！
Could someone please clarify this? Thanks!
推荐答案
规范指出答案取决于:
The specs state that the answer depends:
最大上传文件大小
通过蜂窝连接-5 MB
Over cellular connection - 5 MB
通过具有电池电源的Wi-Fi连接-20 MB
Over Wi-Fi connection with battery power - 20 MB
通过具有外部电源的Wi-Fi连接-100 MB
Over Wi-Fi connection with external power - 100 MB
通过蜂窝网络连接的最大下载大小
Maximum download size over cellular connection
20 MB –如果文件超出此限制，则 属性 转移会自动更改为 ，具有需要Wi-Fi的效果 进行转移.
20 MB – If a file exceeds this limit, the TransferPreferences property for the transfer is automatically changed to AllowBattery, which has the effect of requiring Wi-Fi for the transfer.
在没有外部电源的情况下通过Wi-Fi的最大下载大小
Maximum download size over Wi-Fi without external power
100 MB –对于大于100 MB的文件，必须设置 转移到 无 ，否则传输将失败.如果您不知道转帐的金额 并且有可能超过此限制，则应将值设置为无 ，这意味着仅当电话连接到外部电源并具有Wi-Fi连接时，转移才会继续进行.
100 MB – For files larger than 100 MB, you must set the TransferPreferences property of the transfer to None or the transfer will fail. If you do not know the size of a transfer and it is possible that it could exceed this limit, you should set the value to None, meaning that the transfer will only proceed when the phone is connected to external power and has a Wi-Fi connection.
-马克
这篇关于澄清BackgroundFileTransfer蜂窝数据限制的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！