iOS 5 では、選択状態と通常状態の独自の画像でセグメント コントロールをカスタマイズできます。これを試してください:
UIImage *segmentSelected =
[[UIImage imageNamed:@"segcontrol_sel.png"]
resizableImageWithCapInsets:UIEdgeInsetsMake(0, 15, 0, 15)];
UIImage *segmentUnselected =
[[UIImage imageNamed:@"segcontrol_uns.png"]
resizableImageWithCapInsets:UIEdgeInsetsMake(0, 15, 0, 15)];
UIImage *segmentSelectedUnselected =
[UIImage imageNamed:@"segcontrol_sel-uns.png"];
UIImage *segUnselectedSelected =
[UIImage imageNamed:@"segcontrol_uns-sel.png"];
UIImage *segmentUnselectedUnselected =
[UIImage imageNamed:@"segcontrol_uns-uns.png"];
[[UISegmentedControl appearance] setBackgroundImage:segmentUnselected
forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setBackgroundImage:segmentSelected
forState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segmentUnselectedUnselected
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segmentSelectedUnselected
forLeftSegmentState:UIControlStateSelected
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance]
setDividerImage:segUnselectedSelected
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateSelected
barMetrics:UIBarMetricsDefault];
また、 http: //www.raywenderlich.com/4344/user-interface-customization-in-ios-5 で完全な UI カスタマイズを確認することもでき ます。