1.numberOfComponents：返回UIPickerView当前的列数
NSInteger num = _pickerView.numberOfComponents;
NSLog( @"%d", num);
2. - (NSInteger)numberOfRowsInComponent:(NSInteger)component; 返回component列中有多少行。
NSInteger numInCp = [_pickerView numberOfRowsInComponent:0];
NSLog(@"%d",numInCp);
3. -  (CGSize)rowSizeForComponent:(NSInteger)component; 返回component中一行的尺寸。

CGSize size = [_pickerView rowSizeForComponent:0];
NSLog(@"%@", NSStringFromCGSize(size));

1.numberOfComponents：返回UIPickerView当前的列数
NSInteger num = _pickerView.numberOfComponents;
NSLog( @"%d", num);
2. - (NSInteger)numberOfRowsInComponent:(NSInteger)component; 返回component列中有多少行。
NSInteger numInCp = [_pickerView numberOfRowsInComponent:0];
NSLog(@"%d",numInCp);
3. -  (CGSize)rowSizeForComponent:(NSInteger)component; 返回component中一行的尺寸。

CGSize size = [_pickerView rowSizeForComponent:0];
NSLog(@"%@", NSStringFromCGSize(size));