UISwitch 及其自定义方法

开关（UISwitch）提供了一个简单的开／关UI元素，类似于传统的物理开关，开关的可配置选项很少，应将其用于处理布尔值。我们使用其Value Changed事件来检测开关切换，并通过属性on或实例方法isOn来获取当前值。

 

 

1.UISwitch的初始化

UISwitch *switchView = [[UISwitch alloc] initWithFrame:CGRectMake(54.0f, 16.0f, 100.0f, 28.0f)];

2.设置UISwitch的初始化状态

switchView.on = YES;//设置初始为ON的一边

 3.UISwitch事件的响应

[switchView addTarget:self action:@selector(switchAction:) forControlEvents:UIControlEventValueChanged];

4.自定义

UISwitch类的单薄到我不知道该说什么了。不过，UIControl对象通常是由一系列的子视图构建的。通过导航控件的视图，可以公开的定制通常不能从标准SDK中访问的对象。这种定制依赖于对控件子视图树的理解，通过下面这样的函数可以递归遍历视图树，就可以了解每一个视图了。

- (void)explode:(id)aView level:(int)aLevel {

         for (int i = 0; i < aLevel; i++)

                   printf("-");

         printf("%s:%s/n",[[[aView class] description] UTF8String],[[[aView superclass] description] UTF8String]);

        

         for(UIView *subview in [aView subviews])

                   [self explode:subview level:(aLevel + 1)];

}

初始化级别为0，打出来的结果是：

UISwitch:UIControl

-_UISwitchSlider:UISlider

--UIImageView:UIView

--UIImageView:UIView

--UIView:UIResponder

---UILabel:UIView

---UILabel:UIView

--UIImageView:UIView

 

然后就可以开始封装自定义UISwitch字体和字体颜色的定制功能

@interface UISwitch (extended)

- (void) setAlternateColors:(BOOL) boolean;//这是文档未记录的特性，显示为橘黄色的背景。

@end

 

@interface _UISwitchSlider : UIView

@end

 

@interface UICustomSwitch : UISwitch

- (void) setLeftLabelText: (NSString *) labelText;

- (void) setRightLabelText: (NSString *) labelText;

@end

 

@implementation UICustomSwitch

- (_UISwitchSlider *) slider {

         return [[self subviews] lastObject];

}

- (UIView *) textHolder {

         return [[[self slider] subviews] objectAtIndex:2];

}

- (UILabel *) leftLabel {

         return [[[self textHolder] subviews] objectAtIndex:0];

}

- (UILabel *) rightLabel {

         return [[[self textHolder] subviews] objectAtIndex:1];

}

- (void) setLeftLabelText: (NSString *) labelText {

         [[self leftLabel] setText:labelText];

}

- (void) setRightLabelText: (NSString *) labelText {

         [[self rightLabel] setText:labelText];

}

@end

下面是测试代码：

- (void)loadView

{

         contentView = [[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease];

         contentView.backgroundColor = [UIColor whiteColor];

        

         UICustomSwitch *switchView = [[UICustomSwitch alloc] initWithFrame:CGRectZero];

         [switchView setCenter:CGPointMake(160.0f,170.0f)];

         [contentView addSubview:switchView];

         [switchView release];

 

         switchView = [[UICustomSwitch alloc] initWithFrame:CGRectZero];

         [switchView setCenter:CGPointMake(160.0f,200.0f)];

         [switchView setAlternateColors:YES];

         [contentView addSubview:switchView];

         [switchView release];

        

         switchView = [[UICustomSwitch alloc] initWithFrame:CGRectZero];

         [switchView setCenter:CGPointMake(160.0f,230.0f)];

         [switchView setLeftLabelText: @"YES"];

         [switchView setRightLabelText: @"NO"];

         [contentView addSubview:switchView];

         [switchView release];

        

         switchView = [[UICustomSwitch alloc] initWithFrame:CGRectZero];

         [switchView setCenter:CGPointMake(160.0f,260.0f)];

         [switchView setLeftLabelText: @"ABC"];

         [switchView setRightLabelText: @"DEF"];

         [[switchView rightLabel] setFont:[UIFont fontWithName:@"Georgia" size:16.0f]];

         [[switchView leftLabel] setFont:[UIFont fontWithName:@"Georgia" size:16.0f]];

         [[switchView leftLabel] setTextColor:[UIColor yellowColor]];

         [contentView addSubview:switchView];

         [switchView release];     

        

         self.view = contentView;

}

这样子定制后的结果老强大了（图1）。

                                                       

最后，悲催的事情还是发生了，我们选择了使用资源给出的两张图（图2），结果是我们放弃了那个平滑切换的动画把它做成了一个按钮，点一下换一张图片，记住一个状态。