给按钮的主要三种状态设置图片

UIImage *defaultImg = [UIImage imageNamed:@"button_green"];
UIEdgeInsets insets = UIEdgeInsetsMake(25, 25, 50, 50);
defaultImg = [defaultImg resizableImageWithCapInsets:insets resizingMode:UIImageResizingModeStretch];

UIImage *defaultSelectedImg = [UIImage imageNamed:@"btn_sel"];
defaultSelectedImg = [defaultSelectedImg resizableImageWithCapInsets:insets resizingMode:UIImageResizingModeStretch];

UIImage *defaultNoSelectedImg = [UIImage imageNamed:@"btn_nosel"];
defaultNoSelectedImg = [defaultNoSelectedImg resizableImageWithCapInsets:insets resizingMode:UIImageResizingModeStretch];

[btn setBackgroundImage:defaultImg forState:UIControlStateNormal];
[btn setBackgroundImage:defaultSelectedImg forState:UIControlStateHighlighted];
[btn setBackgroundImage:defaultNoSelectedImg forState:UIControlStateDisabled];

[btn setBackgroundImage:[UMFactory imageWithColor:kThemeBlueColor size:CGSizeZero] forState:UIControlStateNormal];
[btn setBackgroundImage:[UMFactory imageWithColor:kBtnSelectBuleColor size:CGSizeZero] forState:UIControlStateHighlighted];
[btn setBackgroundImage:[UMFactory imageWithColor:kBtnDisableBlueColor size:CGSizeZero] forState:UIControlStateDisabled];
//给视图添加阴影效果
btn.layer.shadowColor = kBlueColor.CGColor;
btn.layer.shadowOffset = CGSizeMake(0.0f, 5.0f);
btn.layer.shadowOpacity = 0.2f;