我如何自定义导航返回按钮在iOS 7及以上没有标题?(即只使用箭头)
self.navigationItem.leftBarButtonItem = self.editButtonItem;
我只是想知道它们是否有self。backbuttonitem;
OR
像这样的东西?
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemBACK
target:self action:@selector(back)];
当前回答
iOS6的简单破解也适用于iOS7:
[UIBarButtonItem.appearance setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];
编辑: 不要使用这种方法。详情见评论。
其他回答
虽然Kyle Begeman的回答完全做到了，但在每个视图控制器中都使用这种代码是相当烦人的。我最终得到了一个简单的UINavigationItem类别。小心，这里有龙!抱歉，我的意思是:
#import <objc/runtime.h>
@implementation UINavigationItem (ArrowBackButton)
static char kArrowBackButtonKey;
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
Method m1 = class_getInstanceMethod(self, @selector(backBarButtonItem));
Method m2 = class_getInstanceMethod(self, @selector(arrowBackButton_backBarButtonItem));
method_exchangeImplementations(m1, m2);
});
}
- (UIBarButtonItem *)arrowBackButton_backBarButtonItem {
UIBarButtonItem *item = [self arrowBackButton_backBarButtonItem];
if (item) {
return item;
}
item = objc_getAssociatedObject(self, &kArrowBackButtonKey);
if (!item) {
item = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStyleBordered target:nil action:NULL];
objc_setAssociatedObject(self, &kArrowBackButtonKey, item, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
return item;
}
@end
所有的答案都不能解决问题。在每个视图控制器中设置后退按钮标题，并且添加偏移量仍然会使下一个视图控制器标题向右移动，这是不可接受的。
这里是使用方法swizzling的方法，只需创建新的扩展UINavigationItem
import UIKit
extension UINavigationItem {
public override class func initialize() {
struct Static {
static var token: dispatch_once_t = 0
}
// make sure this isn't a subclass
if self !== UINavigationItem.self {
return
}
dispatch_once(&Static.token) {
let originalSelector = Selector("backBarButtonItem")
let swizzledSelector = #selector(UINavigationItem.noTitleBackBarButtonItem)
let originalMethod = class_getInstanceMethod(self, originalSelector)
let swizzledMethod = class_getInstanceMethod(self, swizzledSelector)
let didAddMethod = class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))
if didAddMethod {
class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod))
} else {
method_exchangeImplementations(originalMethod, swizzledMethod)
}
}
}
// MARK: - Method Swizzling
struct AssociatedKeys {
static var ArrowBackButtonKey = "noTitleArrowBackButtonKey"
}
func noTitleBackBarButtonItem() -> UIBarButtonItem? {
if let item = self.noTitleBackBarButtonItem() {
return item
}
if let item = objc_getAssociatedObject(self, &AssociatedKeys.ArrowBackButtonKey) as? UIBarButtonItem {
return item
} else {
let newItem = UIBarButtonItem(title: " ", style: UIBarButtonItemStyle.Plain, target: nil, action: nil)
objc_setAssociatedObject(self, &AssociatedKeys.ArrowBackButtonKey, newItem as UIBarButtonItem?, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
return newItem
}
}
}
iOS6的简单破解也适用于iOS7:
[UIBarButtonItem.appearance setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];
编辑: 不要使用这种方法。详情见评论。
为了补充上面托马斯·C的回答，有时只放一个空格是行不通的，你必须不断地添加空格。
当你看到“导航项”下的“栏按钮项-”时，你就知道你成功了。这是在文档大纲(编辑器->显示文档大纲)。一旦你看到上面的图片，你可以删除一些空格，看看它是否仍然有效。
// add left bar button item
try this code:
- (void)viewDidLoad
{
[super viewDidLoad];
UIImage* image_back = [UIImage imageNamed:@"your_leftarrowImage.png"];
CGRect backframe = CGRectMake(250, 9, 15,21);
UIButton *backbutton = [[UIButton alloc] initWithFrame:backframe];
[backbutton setBackgroundImage:image_back forState:UIControlStateNormal];
[backbutton addTarget:self action:@selector(Btn_back:)
forControlEvents:UIControlEventTouchUpInside];
[backbutton setShowsTouchWhenHighlighted:YES];
UIBarButtonItem *backbarbutton =[[UIBarButtonItem alloc] initWithCustomView:backbutton];
self.navigationItem.leftBarButtonItem=backbarbutton;
[backbutton release];
}
-(IBAction)Btn_back:(id)sender
{
[self.navigationController popViewControllerAnimated:YES];
}
