为什么Swift Uipickerview发射多个呼吁委托委员会编号。 numberFrowsComponent？
是我的输出，每次称为委托时打印。
为什么要多次：numberOfComponents＆amp; numberFrowsComponent？
open_plot_picker()...
numberOfComponents: 1
numberOfComponents: 1
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfComponents: 1
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
titleForRow: filtered heart beat only row 1
open_plot_picker() done.
select_plots_UIButton() done.
numberOfComponents: 1
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
titleForRow: filtered heart beat only row 1
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
titleForRow: filtered heart beat only row 1
titleForRow: heart rates only row 2
titleForRow: raw HB and HR row 3
titleForRow: filtered HB and HR row 4
titleForRow: filtered and raw HB row 5
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
Is is my output that prints each time a delegate is called.
Why multiple: numberOfComponents & numberOfRowsInComponent ?
open_plot_picker()...
numberOfComponents: 1
numberOfComponents: 1
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfComponents: 1
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
titleForRow: filtered heart beat only row 1
open_plot_picker() done.
select_plots_UIButton() done.
numberOfComponents: 1
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
titleForRow: filtered heart beat only row 1
numberOfRowsInComponent: 6
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
titleForRow: filtered heart beat only row 1
titleForRow: heart rates only row 2
titleForRow: raw HB and HR row 3
titleForRow: filtered HB and HR row 4
titleForRow: filtered and raw HB row 5
numberOfRowsInComponent: 6
titleForRow: raw heart beat only row 0
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评论（1）
您不应该在调用代表方法的频率。看来它一遍又一遍地要求您的代表排行。只需确保代码是性能的，而不必担心。
You should not care how often your delegate methods are called. It looks like it asks your delegate for the number of rows over and over. Just make sure that code is performant and don't worry about it.