https://github.com/HeshamMegid/HMSegmentedControl
读HMSegmentedControl中，发现如下一行代码
self.edgesForExtendedLayout = UIRectEdgeNone;
查了一下用法：
http://blog.sina.com.cn/s/blog_6291e42d0101f6b0.html
self.title = @"HMSegmentedControl Demo";
self.view.backgroundColor = [UIColor whiteColor];
self.edgesForExtendedLayout = UIRectEdgeNone;
CGFloat viewWidth = CGRectGetWidth(self.view.frame);
// Minimum code required to use the segmented control with the default styling.
HMSegmentedControl *segmentedControl = [[HMSegmentedControl alloc] initWithSectionTitles:@[@"Trending", @"News", @"Library"]];
segmentedControl.frame = CGRectMake(0, 20, viewWidth, 40);
segmentedControl.autoresizingMask = UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleWidth;
[segmentedControl addTarget:self action:@selector(segmentedControlChangedValue:) forControlEvents:UIControlEventValueChanged];
[self.view addSubview:segmentedControl];
self.title = @"HMSegmentedControl Demo";
self.view.backgroundColor = [UIColor whiteColor];
// 注释zhe
//self.edgesForExtendedLayout = UIRectEdgeNone;
CGFloat viewWidth = CGRectGetWidth(self.view.frame);
// Minimum code required to use the segmented control with the default styling.
HMSegmentedControl *segmentedControl = [[HMSegmentedControl alloc] initWithSectionTitles:@[@"Trending", @"News", @"Library"]];
segmentedControl.frame = CGRectMake(0, 84, viewWidth, 40);
segmentedControl.autoresizingMask = UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleWidth;
[segmentedControl addTarget:self action:@selector(segmentedControlChangedValue:) forControlEvents:UIControlEventValueChanged];
[self.view addSubview:segmentedControl];
两者效果图一样，如下图
没有遇到该方法之前，我之前用的是第二种方式，通过添加y值来达到效果。
