建立navigationBar風格的button

//101是往回的箭頭 100跟102都是baritem的按鈕
UIButton *infoButton = [UIButton buttonWithType:101];
[infoButton setFrame:CGRectMake(10,10,infoButton.frame.size.width, infoButton.frame.size.height)];
[infoButton addTarget:self action:@selector(infoButtonTapped) forControlEvents:UIControlEventTouchUpInside];