[button setBackgroundImage:[[UIImage imageNamed:@"buttonline"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10) resizingMode:UIImageResizingModeStretch] forState:UIControlStateNormal];
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UIButton 拉伸图片、让图片不变形
原文：http://www.cnblogs.com/Yishu/p/5917504.html
