UIPickerview循环滚动

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {

    return 1;

}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {

    return self.group.count * 100;

}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {

    return self.group[row % self.groupNames.count];

}

- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component {

    return 50;

}