自定义 UINavigationBar 后退按钮？

Question

我正在制作一个允许用户返回 UINavigationBar 的 iPhone 应用程序。然而，它现在的样子是可怕的。我正在尝试用我自己的图像自定义它（减去默认的 UIBarButtonItem 背景）。我的图片包含了我的自定义背景，但您仍然可以看到左侧和右侧的部分按钮。

UIBarButtonItem *cancelButton = [[[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"back_button_normal.png"] style:UIBarButtonItemStylePlain target:self   action:@selector(cancel:)] autorelease];
self.navigationItem.leftBarButtonItem = cancelButton;  

有没有办法删除那个空间？是否有可能我可以使用 UIButton 以便完全自定义它？我在界面构建器中做了一些事情，我将一个 UIButton 拖到 UINavigationBar 的 rightButton 中，它工作得很好。无论如何我可以通过编程方式做到这一点吗？

谢谢！

它的外观如下：

编辑#1：

UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self action:@selector(cancel:) forControlEvents:UIControlEventTouchDown];
[button setTitle:@"Show View" forState:UIControlStateNormal];
[button setBackgroundImage:[UIImage imageNamed:@"back_button_normal.png"] forState:UIControlStateNormal];

UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithCustomView:button];
[self.navigationItem setLeftBarButtonItem:barButtonItem];

以下是我为 UINavigationBar 制作背景的方法（位于我的 RootViewController 中）：

@implementation UINavigationBar (UINavigationBarCustomDraw)

- (void) drawRect:(CGRect)rect {

[self setTintColor:[UIColor colorWithRed:0.85f green: 0.85f blue:0.85f alpha:1]];

if ([self.topItem.title length] > 0 && ![self.topItem.title isEqualToString:@"Back to ..."]) {
    [[UIImage imageNamed:@"UINavigationBar_background.png"] drawInRect:rect];

    CGRect frame = CGRectMake(0, 0, 320, 44);
    UILabel *label = [[[UILabel alloc] initWithFrame:frame] autorelease];
    [label setBackgroundColor:[UIColor clearColor]];
    label.font = [UIFont boldSystemFontOfSize: 20.0];
    label.shadowColor = [UIColor colorWithWhite:0.0 alpha:1];
    label.textAlignment = UITextAlignmentCenter;
    label.textColor = [UIColor whiteColor];
    label.text = self.topItem.title;
    self.topItem.titleView = label;

} else {
    [[UIImage imageNamed:@"login_button.png"] drawInRect:rect];
    self.topItem.titleView = [[[UIView alloc] init] autorelease];
}
}

@end

Answer 1

结合两个答案并添加返回按钮功能

// Custom Navigation Bar Back Button

// Create Button
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom]; 
button.frame = CGRectMake(0,0,54,32); // width=54, height=32

// Set Button Image
NSString *backButtonURL = [[NSBundle mainBundle]pathForResource:@"back" ofType:@"png"];
UIImage *backButtonImage = [UIImage imageWithContentsOfFile:backButtonURL];
[button setBackgroundImage:backButtonImage forState:UIControlStateNormal];

// Important: Set Button Action to go back
[button addTarget:self.navigationController action:@selector(popViewControllerAnimated:) forControlEvents:UIControlEventTouchUpInside];

Answer 2

如果你想通过 obj-c 将UIButton 添加到导航栏，你的代码应该是这样的：

UIButton *button = /* initialize your button */

UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithCustomView:button];
[self.navigationItem setLeftBarButtonItem:barButtonItem];

Answer 3

问题是您使用的是UIButtonTypeRoundedRect 而不是UIButtonTypeCustom。您可能还想使用：

UIImage *image = [UIImage imageNamed:@"back_button_normal.png"]
button.frame = CGRectMake(0, 0, image.size.width, image.size.height);