使用 UIAppearance 分别自定义 UIBarButtonItem“完成”样式和“普通”样式

Question

我知道如何使用-setBackgroundImage: forState: barMetrics: 自定义UIBarButtonItem，但我想为UIBarButtonItemStyleDone 和UIBarButtonItemStylePlain 使用不同的图像。

有没有办法使用UIAppearance 协议来实现这一点？还是每次我想要“完成”样式按钮时都必须设置图像？

（我尝试过使用如下代码：

[[UIBarButtonItem appearance] setBackgroundImage:image forState:UIControlStateNormal barMetrics:UIBarButtonItemStyleDone];

但这只是将每个条形按钮设置为“完成”图像。）

谢谢！

Answer 1

在iOS 6中可以使用UIBarButtonItem类的新方法：

- (void)setBackgroundImage:(UIImage *)backgroundImage
                  forState:(UIControlState)state
                     style:(UIBarButtonItemStyle)style
                barMetrics:(UIBarMetrics)barMetrics

它为指定的状态、样式和指标设置背景图像。 更多详情可in the Apple docs

所以要改变所有 UIBarButtonItems 的外观，你可以使用类似的东西：

UIImage *doneBackgroundImage = [[UIImage imageNamed:@"button_done.png"]
   resizableImageWithCapInsets:UIEdgeInsetsMake(0, 4, 0, 4)];

[[UIBarButtonItem appearance] setBackgroundImage:doneBackgroundImage
                                            forState:UIControlStateNormal
                                               style:UIBarButtonItemStyleDone
                                          barMetrics:UIBarMetricsDefault];

Answer 2

适用于 IOS5*

我发现的唯一方法是使用 UIBarButtonItem 类别：

UIBarButtonItem+Appearance.h

#import <Foundation/Foundation.h>

@interface UIBarButtonItem (Appearance)

+ (void) setupAppearance;

@end

UIBarButtonItem+Appearance.m

#import "UIBarButtonItem+Appearance.h"
#import <objc/runtime.h>

@implementation UIBarButtonItem (Appearance)

+ (void) setupAppearance {
    [[UIBarButtonItem appearance]  setBackgroundImage: [[UIImage imageNamed:@"customButton"]
                                                                  resizableImageWithCapInsets: UIEdgeInsetsMake(8, 8, 8, 8)]
                                                       forState: UIControlStateNormal
                                                     barMetrics: UIBarMetricsDefault];

    [[UIBarButtonItem appearance]  setBackgroundImage: [[UIImage imageNamed:@"customButtonHiglhighted"]
                                                                  resizableImageWithCapInsets: UIEdgeInsetsMake(8, 8, 8, 8)]
                                                       forState: UIControlStateHighlighted
                                                     barMetrics: UIBarMetricsDefault];



    Class klass = objc_getClass("UIBarButtonItem");
    Method targetMethod = class_getInstanceMethod(klass, @selector(setStyle:));
    Method newMethod = class_getInstanceMethod(klass, @selector(__setStyle:));
    method_exchangeImplementations(targetMethod, newMethod);
}

- (void) __setStyle:(UIBarButtonItemStyle)style {
    [self __setStyle:style];

    if(style == UIBarButtonItemStyleDone) {
        [self setBackgroundImage:[[UIImage imageNamed:@"customDoneButton"] resizableImageWithCapInsets: UIEdgeInsetsMake(8, 8, 8, 8)]
                        forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
        [self setBackgroundImage:[UIImage imageNamed:@"customDoneButtonClicked"]
                        forState:UIControlStateHighlighted barMetrics:UIBarMetricsDefault];
    } else {
        [self setBackgroundImage:[[UIImage imageNamed:@"customButton"] resizableImageWithCapInsets: UIEdgeInsetsMake(8, 8, 8, 8)]
                        forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
        [self setBackgroundImage:[UIImage imageNamed:@"customButtonHighlighted"]
                        forState:UIControlStateHighlighted barMetrics:UIBarMetricsDefault];
    }
}

@end

希望这是您正在寻找的。 此解决方案的功劳归于https://gist.github.com/2633081