iphone - 后退按钮的自定义 UIBarButtonItem

Question

我正在尝试为导航栏中的后退按钮使用自定义项目。

UIImage *backButtonImage = [UIImage imageNamed:@"backbutton.png"];
UIBarButtonItem *customItem = [[UIBarButtonItem alloc] initWithImage:backButtonImage style:UIBarButtonItemStylePlain target:nil action:nil];
[self.navigationItem setBackBarButtonItem: customItem];
[customItem release];

我最终得到的是我的图像，周围有边框。它看起来像这样（我的图像是后退按钮）：

如何摆脱边框？我做错了什么？

Answer 1

您的图像出现在后退按钮内部，并且它显然（从您的屏幕截图来看）与后退按钮的大小不同。

您可能想隐藏后退按钮，然后将其替换为“左栏按钮”。

代码：

UIImage *backButtonImage = [UIImage imageNamed:@"backbutton.png"];
UIBarButtonItem *customItem = [[UIBarButtonItem alloc] initWithImage:backButtonImage style:UIBarButtonItemStylePlain target:self.navigationController action:@selector(popViewControllerAnimated:)];
[self.navigationController setHidesBackButton:YES];
[self.navigationItem setLeftBarButtonItem: customItem];
[customItem release];

Answer 2

这是我的解决方案，基于 Jorge 的代码。

我在 UIViewController 上创建了一个简单的类别：

UIViewController+ImageBackButton.h

#import <UIKit/UIKit.h>

@interface UIViewController (ImageBackButton)

- (void)setUpImageBackButton;

@end

UIViewController+ImageBackButton.m

#import "UIViewController+ImageBackButton.h"

@implementation UIViewController (ImageBackButton)

- (void)setUpImageBackButton
{
    UIButton *backButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 34, 26)];
    [backButton setBackgroundImage:[UIImage imageNamed:@"back_arrow.png"] forState:UIControlStateNormal];
    UIBarButtonItem *barBackButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
    [backButton addTarget:self action:@selector(popCurrentViewController) forControlEvents:UIControlEventTouchUpInside];
    self.navigationItem.leftBarButtonItem = barBackButtonItem;
    self.navigationItem.hidesBackButton = YES;
}

- (void)popCurrentViewController
{
    [self.navigationController popViewControllerAnimated:YES];
}

@end

现在您所要做的就是 #在所有视图控制器或其他视图控制器继承的自定义基本视图控制器类中导入 UIViewController+ImageBackButton.h 并实现 viewWillAppear: 方法：

- (void)viewWillAppear:(BOOL)animated
{
    [self setUpImageBackButton];
}

仅此而已。现在你到处都有一个图像后退按钮。无国界。享受！

Answer 3

这是更新版本。这包括设置目标、字体大小等。

此外，它还反映出 setHidesBackButton 不能作为 navigationController 的属性使用。

UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
UIImage *backButtonBackgroundImg = [UIImage imageNamed:@"BackButton.png"];
backButton.frame = CGRectMake(0.0f, 0.0f, backButtonBackgroundImg.size.width, backButtonBackgroundImg.size.height);
[backButton setBackgroundImage:backButtonBackgroundImg forState:UIControlStateNormal];
[backButton addTarget:self action:@selector(didTouchUpInsideBackButton:) forControlEvents:UIControlEventTouchUpInside];
backButton.titleLabel.font = [UIFont boldSystemFontOfSize:[UIFont smallSystemFontSize]];
[backButton setTitle:@"MyTitle" forState:UIControlStateNormal];

self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];

请注意，这是来自 ARC 项目，因此对象上没有发布等。

Answer 4

我创建了一个 UINavigationBar 类别，在每个 viewController 中的 viewWillAppear 中调用它。我用来更改后退按钮外观的代码如下：

UIButton *backButton = [[UIButton alloc] initWithFrame:CGRectMake( your button frame)];
[backButton setBackgroundImage:[UIImage imageNamed:@"your image name"] forState:UIControlStateNormal];
UIBarButtonItem *barBackButtonItem = [[UIBarButtonItem alloc] initWithCustomView: backButton];
[backButton addTarget:delegate action:@selector(backButtonPressed) forControlEvents:UIControlEventTouchUpInside];
self.topItem.leftBarButtonItem = barBackButtonItem;
self.topItem.hidesBackButton = YES;

在 iOS 6 下完美运行。