问NSURLSessionTask:添加到iOS11中的“进度”属性似乎毫无用处
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Stack Overflow用户

提问于 2018-03-03 11:37:26

回答 1查看 166关注 0票数 1

在NSURLSessionTask中，iOS11中的一个新属性是progress属性：

对总体任务进度的描述 @property(只读，强) NSProgress *progress；

当在1025886字节中的781334字节查询时，输出如下所示：

<NSProgress: 0x1c0324ec0> : Parent: 0x0 / Fraction completed: 0.0000 / Completed: 0 of 1025886  
  <NSProgress: 0x1c0325140> : Parent: 0x1c0324ec0 / Fraction completed: 0.0000 / Completed: 781334 of -1  
  <NSProgress: 0x1c03251e0> : Parent: 0x1c0324ec0 / Fraction completed: 0.0000 / Completed: 0 of 100

注意，fractionCompleted是0.000而不是0.762。

当数据任务完成时，它的progress属性的输出如下所示：

<NSProgress: 0x1c4131440> : Parent: 0x0 / Fraction completed: 0.0000 / Completed: 5 of 1142597  
  <NSProgress: 0x1c4131580> : Parent: 0x1c4131440 / Fraction completed: 0.0000 / Completed: -1 of -1

注：Completed: 5 of 1142597。

NSURLSessionTask的进度报告似乎毫无用处。因此，为了在iOS11中向UI报告进度，我仍然必须编写与以前相同的样板代码。那么，这个新属性的目的是什么呢？

cocoa

ios11

回答 1

Stack Overflow用户

发布于 2018-06-15 02:14:50

当我向苹果报告这个错误时，我创建了一个示例项目，它位于这里：https://github.com/mickeyl/iOS-Bug-Example-Projects/tree/master/NSURLSessionTask-Progress-Broken

下面是用上面的示例项目创建的日志的摘录：

2018-06-15 12:02:17.641650+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462000019 of 1073741824
2018-06-15 12:02:17.641917+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462002915 of 1073741824
2018-06-15 12:02:17.642193+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462005811 of 1073741824
2018-06-15 12:02:17.642476+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462008707 of 1073741824
2018-06-15 12:02:17.642828+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462014499 of 1073741824
2018-06-15 12:02:17.643083+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462017395 of 1073741824
2018-06-15 12:02:17.643344+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462020291 of 1073741824
2018-06-15 12:02:17.643611+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462023187 of 1073741824
2018-06-15 12:02:17.643878+0200 NSURLSessionTask-Progress-Broken[74670:2636851] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 0.4588 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 0.4303 / Completed: 462026083 of 1073741824

[...]

2018-06-15 12:03:29.216655+0200 NSURLSessionTask-Progress-Broken[74670:2636247] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 1.0000 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 1.0000 / Completed: 1073727891 of 1073741824
2018-06-15 12:03:29.217201+0200 NSURLSessionTask-Progress-Broken[74670:2636854] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 1.0000 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 1.0000 / Completed: 1073730787 of 1073741824
2018-06-15 12:03:29.217407+0200 NSURLSessionTask-Progress-Broken[74670:2636854] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 1.0000 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 1.0000 / Completed: 1073733683 of 1073741824
2018-06-15 12:03:29.217889+0200 NSURLSessionTask-Progress-Broken[74670:2637014] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 1.0000 / Completed: 5 of 100  
  <NSProgress: 0x600000131440> : Parent: 0x600000131800 / Fraction completed: 1.0000 / Completed: 1073739475 of 1073741824
2018-06-15 12:03:29.218147+0200 NSURLSessionTask-Progress-Broken[74670:2637014] Progress = <NSProgress: 0x600000131800> : Parent: 0x0 / Fraction completed: 1.0000 / Completed: 100 of 100

在这里，我们可以观察到--由于某种原因--对于一个NSURLSessionTask来说，有一个父NSProgress和一个子NSProgress创建。虽然子进程包含了适当的信息，但在大多数情况下，父进程似乎坚持5/100个单元。至少它使fractionCompleted在某种程度上是正确的。

因此:当坚持子NSProgress时，progress属性有点有用。

不幸的是，我需要支持iOS一直到9，这就是为什么我必须创建我自己的替代品无论如何。

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原文链接：

https://stackoverflow.com/questions/49088405

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