iPhone 中 iPhone OS 4.0 的导航栏中不可见后退按钮

Question

在我的应用程序（基于视图）中，后退按钮在导航栏中不可见。如果我单击该按钮，操作就会正常进行。这对我来说很奇怪。后退按钮在 iPhone OS 3.0 和其他操作系统中可见且正常工作。（OS 4.0 除外）。我目前使用 iPhone OS 4.0。

这是我的代码：

UIButton *btn=[[UIButton alloc] init];

[btn setImage:[UIImage imageNamed:@"Back.png"] forState:UIControlStateNormal];

[btn addTarget:self action:@selector(backAction) forControlEvents:UIControlEventTouchUpInside];
[btn setImageEdgeInsets:UIEdgeInsetsMake(0, 70, 0, 20)];
UIBarButtonItem *b=[[UIBarButtonItem alloc] initWithCustomView:btn];    
self.navigationItem.leftBarButtonItem=b;
[b release];
[btn release]; 

注意：它仅适用于 iPhone OS 4.0。那么我怎样才能实现这一目标呢？

Answer 1

只需将这段代码替换到任何你想要的地方，它就可以在 OS 4.0 中正常工作。

UIButton *btn=[[UIButton alloc] initWithFrame:CGRectMake(0, 0, 70, 40)];

UIView *myView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 70, 40)];

[myView addSubview:btn];

UIImageView *myImage = [[UIImageView alloc] initWithFrame:CGRectMake(0,5,50,30)];

[myImage setImage:[UIImage imageNamed:@"Back.png"]];

[myView addSubview:myImage];

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

UIBarButtonItem *b1 = [[UIBarButtonItem alloc] initWithCustomView:myView];

self.navigationItem.leftBarButtonItem = b1;

[btn release];

[b1 release];

[myView release];

[myImage release];

我希望它能帮助你。

Answer 2

UIButton *btn=[[UIButton alloc] initWithFrame:CGRectMake(0, 0, 44, 40)];
[btn setImage:[UIImage imageNamed:@"info44.png"] forState:UIControlStateNormal];
[btn setImage:[UIImage imageNamed:@"info44_glowing.png"] forState:UIControlStateHighlighted];   
[btn addTarget:[AppDelegate sharedAppDelegate]  action:@selector(settingAction:) forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *settingButton = [[UIBarButtonItem alloc] initWithCustomView:btn];
self.navigationItem.leftBarButtonItem = settingButton;
[btn release];
[settingButton release];