按钮继承自UIControl，所以其样式设置也跟UIView不一样！！
/创建导航栏右边按钮
UIButton* barButtonItemCancel = [UIButton buttonWithType:UIButtonTypeCustom];
//设置按钮标题
[barButtonItemCancel setTitle:AppLocalizedString(@"Cancel") forState:UIControlStateNormal];
//设置按钮标题字体
barButtonItemCancel.titleLabel.font = [UIFont systemFontOfSize:12];
//设置按钮标题颜色
[barButtonItemCancel setTitleColor:kMainColorOfApp forState:UIControlStateNormal];
//设置按钮标题对齐样式
barButtonItemCancel.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
//设置按钮背景色
[barButtonItemCancel setBackgroundColor:[UIColor redColor]];
[barButtonItemCancel addTarget:self action:@selector(onClickCancel) forControlEvents: UIControlEventTouchUpInside];
