Swift3 GCD全局队列(global)的优先级

Swift 3 在GCD的语法上改变了很多，更加贴近了swift的语法，而且关于队列的优先级也改变了不少。

原先的GCD只有四个优先级，high，default，low，BACkground

然而现在的GCD有六个优先级，BACkground，utility，default，userInitiated，userInteractive，unspecified

经过试验，得出了几个结论，

userInteractive的优先级最高，相当于high

BACkground的优先级最低，相当于原来的BACkground

default的优先级高于unspecified，userInitiated，utility

unspecified的优先级高于userInitiated，utility

userInitiated的优先级高于utility

@H_616_121@userInteractive>@H_616_121@default>@H_616_121@unspecified>@H_616_121@userInitiated>@H_616_121@utility>BACkground

@H_616_121@另附实验代码，若有不正确的地方欢迎指正

@H_616_121@

for i in 1...10 {
       DispatchQueue.global(qos: DispatchQos.QoSClass.default).async {
           NSLog("DispatchQos.QoSClass.default,%d",i)
       }
            
       DispatchQueue.global(qos: DispatchQos.QoSClass.BACkground).async {
           NSLog("DispatchQos.QoSClass.BACkground,i)
       }
            
       DispatchQueue.global(qos: DispatchQos.QoSClasS.Unspecified).async {
           NSLog("DispatchQos.QoSClasS.Unspecified,i)
       }
            
       DispatchQueue.global(qos: DispatchQos.QoSClasS.UserInitiated).async {
           NSLog("DispatchQos.QoSClasS.UserInitiated,i)
       }
            
       DispatchQueue.global(qos: DispatchQos.QoSClasS.UserInteractivE).async {
           NSLog("DispatchQos.QoSClasS.UserInteractive,i)
       }
            
       DispatchQueue.global(qos: DispatchQos.QoSClasS.Utility).async {
           NSLog("DispatchQos.QoSClasS.Utility,i)
       }
}

试验数据：

2016-11-15 11:46:12.927070 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,1
2016-11-15 11:46:12.927363 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,2
2016-11-15 11:46:12.927407 GraphicsContext[2099:635171] DispatchQos.QoSClasS.UserInteractive,3
2016-11-15 11:46:12.927490 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,4
2016-11-15 11:46:12.927674 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,5
2016-11-15 11:46:12.927780 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,6
2016-11-15 11:46:12.927868 GraphicsContext[2099:635172] DispatchQos.QoSClasS.UserInteractive,7
2016-11-15 11:46:12.927871 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,8
2016-11-15 11:46:12.928016 GraphicsContext[2099:635172] DispatchQos.QoSClasS.UserInteractive,9
2016-11-15 11:46:12.928138 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInteractive,10
2016-11-15 11:46:12.928719 GraphicsContext[2099:635113] DispatchQos.QoSClass.default,1
2016-11-15 11:46:12.928817 GraphicsContext[2099:635166] DispatchQos.QoSClasS.Unspecified,1
2016-11-15 11:46:12.928924 GraphicsContext[2099:635172] DispatchQos.QoSClasS.UserInitiated,1
2016-11-15 11:46:12.929190 GraphicsContext[2099:635173] DispatchQos.QoSClass.default,2
2016-11-15 11:46:12.929225 GraphicsContext[2099:635171] DispatchQos.QoSClasS.Utility,1
2016-11-15 11:46:12.929723 GraphicsContext[2099:635174] DispatchQos.QoSClasS.Unspecified,2
2016-11-15 11:46:12.930104 GraphicsContext[2099:635176] DispatchQos.QoSClasS.UserInitiated,2
2016-11-15 11:46:12.930131 GraphicsContext[2099:635175] DispatchQos.QoSClasS.Utility,2
2016-11-15 11:46:12.930641 GraphicsContext[2099:635177] DispatchQos.QoSClass.default,3
2016-11-15 11:46:12.931705 GraphicsContext[2099:635179] DispatchQos.QoSClasS.Unspecified,3
2016-11-15 11:46:12.931857 GraphicsContext[2099:635180] DispatchQos.QoSClasS.UserInitiated,3
2016-11-15 11:46:12.932196 GraphicsContext[2099:635181] DispatchQos.QoSClass.default,4
2016-11-15 11:46:12.932277 GraphicsContext[2099:635178] DispatchQos.QoSClasS.Utility,3
2016-11-15 11:46:12.932779 GraphicsContext[2099:635183] DispatchQos.QoSClasS.Unspecified,4
2016-11-15 11:46:12.932889 GraphicsContext[2099:635182] DispatchQos.QoSClasS.UserInitiated,4
2016-11-15 11:46:12.933215 GraphicsContext[2099:635185] DispatchQos.QoSClass.default,5
2016-11-15 11:46:12.933027 GraphicsContext[2099:635184] DispatchQos.QoSClasS.Utility,4
2016-11-15 11:46:12.933423 GraphicsContext[2099:635113] DispatchQos.QoSClasS.Unspecified,5
2016-11-15 11:46:12.933586 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInitiated,5
2016-11-15 11:46:12.933709 GraphicsContext[2099:635172] DispatchQos.QoSClass.default,6
2016-11-15 11:46:12.933831 GraphicsContext[2099:635173] DispatchQos.QoSClasS.Unspecified,6
2016-11-15 11:46:12.933976 GraphicsContext[2099:635174] DispatchQos.QoSClasS.UserInitiated,6
2016-11-15 11:46:12.934095 GraphicsContext[2099:635176] DispatchQos.QoSClass.default,7
2016-11-15 11:46:12.934242 GraphicsContext[2099:635177] DispatchQos.QoSClasS.Unspecified,7
2016-11-15 11:46:12.934356 GraphicsContext[2099:635179] DispatchQos.QoSClasS.UserInitiated,7
2016-11-15 11:46:12.934503 GraphicsContext[2099:635180] DispatchQos.QoSClass.default,8
2016-11-15 11:46:12.934611 GraphicsContext[2099:635171] DispatchQos.QoSClasS.Utility,5
2016-11-15 11:46:12.934701 GraphicsContext[2099:635175] DispatchQos.QoSClasS.Utility,6
2016-11-15 11:46:12.937166 GraphicsContext[2099:635186] DispatchQos.QoSClasS.Unspecified,8
2016-11-15 11:46:12.937476 GraphicsContext[2099:635188] DispatchQos.QoSClasS.UserInitiated,8
2016-11-15 11:46:12.937521 GraphicsContext[2099:635187] DispatchQos.QoSClasS.Utility,7
2016-11-15 11:46:12.937682 GraphicsContext[2099:635181] DispatchQos.QoSClass.default,9
2016-11-15 11:46:12.937868 GraphicsContext[2099:635183] DispatchQos.QoSClasS.Unspecified,9
2016-11-15 11:46:12.937987 GraphicsContext[2099:635182] DispatchQos.QoSClasS.UserInitiated,9
2016-11-15 11:46:12.938110 GraphicsContext[2099:635185] DispatchQos.QoSClass.default,10
2016-11-15 11:46:12.938262 GraphicsContext[2099:635113] DispatchQos.QoSClasS.Unspecified,10
2016-11-15 11:46:12.938381 GraphicsContext[2099:635166] DispatchQos.QoSClasS.UserInitiated,10
2016-11-15 11:46:12.938692 GraphicsContext[2099:635178] DispatchQos.QoSClasS.Utility,8
2016-11-15 11:46:12.938837 GraphicsContext[2099:635184] DispatchQos.QoSClasS.Utility,9
2016-11-15 11:46:12.941483 GraphicsContext[2099:635174] DispatchQos.QoSClasS.Utility,10
2016-11-15 11:46:12.949181 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,1
2016-11-15 11:46:12.949734 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,2
2016-11-15 11:46:12.950257 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,3
2016-11-15 11:46:12.950775 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,4
2016-11-15 11:46:12.951348 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,5
2016-11-15 11:46:12.952512 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,6
2016-11-15 11:46:12.953108 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,7
2016-11-15 11:46:12.953659 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,8
2016-11-15 11:46:12.954176 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,9
2016-11-15 11:46:12.954890 GraphicsContext[2099:635115] DispatchQos.QoSClass.BACkground,10