UIButton 拉伸图片、让图片不变形

 CGFloat top = 10; // 顶端盖高度
 CGFloat bottom = 10 ; // 底端盖高度
 CGFloat left = 10; // 左端盖宽度
 CGFloat right = 10; // 右端盖宽度
 UIEdgeInsets insets = UIEdgeInsetsMake(top, left, bottom, right);
[optionButton setBackgroundImage:[[UIImage imageNamed:@"hf_segment_control_left_normal"] resizableImageWithCapInsets:insets] forState:UIControlStateNormal];

[button setBackgroundImage:[[UIImage imageNamed:@"buttonline"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10) resizingMode:UIImageResizingModeStretch] forState:UIControlStateNormal];

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