IOS中图片作为button的背景图拉伸

适用于IOS6.0
UIImage *image2 = [UIImage
imageNamed:@"header_left_back_normal"];
CGFloat top = 0;
// 顶端盖高度
CGFloat bottom = 0 ;
// 底端盖高度
CGFloat left = 15;
// 左端盖宽度
CGFloat right = 15;
// 右端盖宽度
UIEdgeInsets insets =
UIEdgeInsetsMake(top, left, bottom, right);
image2 = [image2 resizableImageWithCapInsets:insets
resizingMode:UIImageResizingModeTile];
// UIImageResizingModeStretch：拉伸模式，通过拉伸UIEdgeInsets指定的矩形区域来填充图片
// UIImageResizingModeTile：平铺模式，通过重复显示UIEdgeInsets指定的矩形区域来填充图片

UIButton *backBtn2 = [UIButton
buttonWithType:UIButtonTypeCustom];
backBtn2.frame = CGRectMake(0,
100, screenWidth,
29);
[backBtn2 setBackgroundImage:image2
forState:UIControlStateNormal];
[backBtn2 setBackgroundImage:image2
forState:UIControlStateSelected];
[backBtn2 addTarget:self
action: @selector(customDefaultBackButtonClick)
forControlEvents: UIControlEventTouchUpInside];
[backBtn2 setTitle:@"讨论组"
forState:UIControlStateNormal];
[backBtn2.titleLabel setFont:[UIFont
fontWithName:@"Arial"
size:13]];

[self.view
addSubview:backBtn2];