1. This display data
1. In it, there are data source protocol and proxy protocol. In the past, how to use it in TableView,
How did we do it before,
1) Step 1: Did you set the data,
Set the data source object, proxy object, and then,
Then, our Main.storyboard, right click,
Drag this data source object to the controller
The proxy object is also dragged into the controller
Then, in the controller, do you abide by the corresponding protocol?
Then, let’s go in and take a look, it’s the data source proxy protocol,
Hold down the command key, jump in,
There are several data source methods,
only two,
1) numberOfComponentsInPickerView: returns how many groups you have
For this PickerView, its column by column is a group,
A column is a group,
2) numberOfRowsInComponent: how many rows per group,
Then, inside the PickerViewDelegate,
Are these proxy methods,
Then, do we want to display some text content now,
Let's see, which one do you need to use?
1) Is the return type NSString, and then,
titleForRow: What content is displayed in each row,
What headings are displayed on each line,
Now you know what to do, follow its protocol,
Delete this didReceiveMemoryWarning method
Is there a way to achieve it, on the line,
what, is the first one
1）numberOfComponentsInPickerView：
returns how many groups there are, right,
2) Then, there is another one called, first enter a minus sign pickerView,
numberOfRowsInComponent：
Return how many rows are in each group:
But, have you noticed that in our PickerView, its display content is not in the proxy method,
Inside the TableView, where,
Return the content displayed by each row of Cell, whether it is in the data source method,
Here's a little difference between them,
Next, what to do,
1) numberOfComponents: whether to return how many groups,
How do you determine this group?
Have a look inside your array,
