自定义导航栏按钮UIBarButtonItem 文字或图片

在4.0里定义导航条按钮通常是生成普通按钮，再用它生成导航条专用按钮。

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setBackgroundImage:[UIImage imageNamed:@"button_main.png"]
forState:UIControlStateNormal];
[button addTarget:self action:@selector(GotoSettings)
forControlEvents:UIControlEventTouchUpInside];
button.frame = CGRectMake(x, y, x1, x2);

UIBarButtonItem *menuButton = [[UIBarButtonItem alloc] initWithCustomView:menu];
self.navigationItem.rightBarButtonItem = menuButton;

[button release];
[menuButton release];

如果是在导航条一边创建多个button，在4.0里是通过segmentcontrol来间接实现

UISegmentedControl *SegmentedControl = [[UISegmentedControl alloc] initWithItems:
[NSArray arrayWithObjects:
@"开始",
@"暂停", nil]];
[SegmentedControl addTarget:self action:@selector(segmentAction:)
forControlEvents:UIControlEventValueChanged];
SegmentedControl.frame = CGRectMake(0, 0, 80, 30);
SegmentedControl.segmentedControlStyle = UISegmentedControlStyleBar;
SegmentedControl.momentary = YES;
SegmentedControl.tintColor = [UIColor colorWithHue:0.6 saturation:0.33 brightness:0.69 alpha:0];
//defaultTintColor = [segmentedControl.tintColor retain];    // keep track of this for later
UIBarButtonItem *segmentBarItem = [[UIBarButtonItem alloc]
initWithCustomView:SegmentedControl];
self.navigationItem.rightBarButtonItem = segmentBarItem;

之后 通过Action方法判断是哪个button被按下

- (void)segmentAction:(id)sender
{

//NSLog(@"segmentAction: selected segment = %d", [sender selectedSegmentIndex]);
if ([sender selectedSegmentIndex] == 0) {
//[self startAll];

}else if ([sender selectedSegmentIndex] == 1) {
//[self stopAll];
}

}

在iOS 5.0中，导航条引入了新的方法 setLeftBarButtonItems:animated:和setRightBarButtonItems:animated:来直接定义左右侧的多个button，方便了许多

UIBarButtonItem *startBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemPlay target:self action:@selector(startDownloadAll)];
UIBarButtonItem *pauseBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemPause target:self action:@selector(stopDownloadAll)];
[self.navigationItem setRightBarButtonItems:[NSArray arrayWithObjects: pauseBtn,startBtn,nil]];