代理方法
// 标题
- (NSString *)segmentView:(XMFSegmentView *)segmentView titleOfIndex:(NSUInteger)index;
// 每个item的宽度
- (CGFloat)segmentView:(XMFSegmentView *)segmentView widthOfIndex:(NSUInteger)index;
// item的数量
- (NSUInteger)numberOfItemsInSegmentView:(XMFSegmentView *)segmentView;
// 点击item
- (void)segmentView:(XMFSegmentView *)segmentView didSelectItemsAtIndex:(NSUInteger)index;
// 高亮的颜色
- (UIColor *)highlightColorInSegmentView:(XMFSegmentView *)segmentView;
// 标题字体颜色
- (UIColor *)fontColorInSegmentView:(XMFSegmentView *)segmentView ;