调整导航条上leftBarButtonItem和rightBarButtonItem与屏幕边界的间距

UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];

/**

* 设置frame只能控制按钮的大小

*/

btn.frame= CGRectMake(0, 0, 40, 44);

[btn addTarget:self action:@selector(buttonClicked) forControlEvents:UIControlEventTouchUpInside];

UIBarButtonItem *btn_right = [[UIBarButtonItem alloc] initWithCustomView:btn];

UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc]

initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace

target:nil action:nil];

/**

* width为负数时，相当于btn向右移动width数值个像素，由于按钮本身和边界间距为5pix，所以width设为-5时，间距正好调整

* 为0；width为正数时，正好相反，相当于往左移动width数值个像素

*/

negativeSpacer.width = -5;

self.navigationItem.rightBarButtonItems = [NSArray arrayWithObjects:negativeSpacer, btn_right, nil];

[btn_right release];