UIPickerView 中的 reloadComponent 方法
帮助文档中是这么说的：
调用此方法会导致选取器视图向委托查询给定组件的新数据。
我在以下位置添加了一些断点：
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
当我调用 reloadComponent 方法时，但没有一个断点被调用。问题是什么？
In the help document, it says that:
Calling this method causes the picker view to query the delegate for new data for the given component.
I added some breakpoints at:
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
when I call the reloadComponent method but none of them were called. What is the problem?
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您需要将 pickerView 的 dataSource 属性设置为实现 UIPickerViewDataSource 协议。
我认为文档指的是软件工程设计模式中的“委托”，而不是类的属性
delegate，这可能有点误导。You need to set the
dataSourceproperty of the pickerView to an instance of a class that implements the UIPickerViewDataSource protocol.I think the documentation is referring to a "delegate" as in the software engineering design pattern of delegation, as opposed to the property
delegateof the class which is probably a little misleading.