实例020 实现视图嵌套

实例说明

在iOS应用中，在一个UIView里面可以包含许多的Subview（其他的UIView），而这些Subview彼此之间有所谓的阶层关系，这有点类似于绘图软件中图层的概念。例如，在下面的代码中，演示了几个在管理图层（Subview）上常用的方法。

（1）新增和移除Subview。

//将Subview从当前的UIView中移除
 [Subview removeFromSuperview];
//替UIView增加一个Subview
 [UIView addSubview:Subview];

（2）在UIView中将Subview往前或者往后移动一个图层，往前移动会覆盖住较后层的Subview，而往后移动则会被较上层的Subview所覆盖。

//将Subview往前移动一个图层（与它的前一个图层对调位置）
 [UIView bringSubviewToFront:Subview];
 //将Subview往后移动一个图层（与它的后一个图层对调位置）
 [UIView sendSubviewToBack:Subview];

（3）在UIView中使用索引Index交换两个Subview彼此的图层层级。

//交换两个图层
 [UIView exchangeSubviewAtIndex:indexA withSubviewAtIndex:indexB];

（4）使用Subview的变数名称取得它在UIView中的索引值（Index）。

//取得Index
 NSInteger index = [[UIView subviews] indexOfObject:Subview名称];

在本实例中，演示了使用addSubview方法添加视图，以实现视图嵌套的具体过程。

具体实现

实例文件UIkitPrjSubviews.h的实现代码如下所示。

#import "SampleBaseController.h"
@interface UIKitPrjSubviews : SampleBaseController
{
 @private
}
@end

实例文件UIkitPrjSubviews.m的实现代码如下所示。

#import "UIKitPrjSubviews.h"
#pragma mark ----- Private Methods Definition -----
@interface UIKitPrjSubviews ()
- (void)button11DidPush:(id)sender;
- (void)button111DidPush:(id)sender;
- (void)button112DidPush:(id)sender;
- (void)button1121DidPush:(id)sender;
- (void)button1122DidPush:(id)sender;
- (void)alertMessage:(UIButton*)button;
@end
#pragma mark ----- Start Implementation For Methods -----
@implementation UIKitPrjSubviews
- (void)viewDidLoad {
  [super viewDidLoad];
  self.view.backgroundColor = [UIColor blackColor];
  // 追加1-1按钮
  UIButton* button11 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  button11.frame = CGRectMake( 10, 10, 300, 300 );
  [button11 setTitle:@"1-1" forState:UIControlStateNormal];
  [button11 addTarget:self
              action:@selector(button11DidPush:)
      forControlEvents:UIControlEventTouchUpInside];
  [self.view addSubview:button11];
  // 追加1-1-1按钮
  UIButton* button111 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  button111.frame = CGRectMake( 20, 20, 260, 100 );
  [button111 setTitle:@"1-1-1" forState:UIControlStateNormal];
  [button111 addTarget:self
              action:@selector(button111DidPush:)
      forControlEvents:UIControlEventTouchUpInside];
  [button11 addSubview:button111];
  // 追加1-1-2按钮
  UIButton* button112 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  button112.frame = CGRectMake( 20, 180, 260, 100 );
  [button112 setTitle:@"1-1-2" forState:UIControlStateNormal];
  [button112 addTarget:self
              action:@selector(button112DidPush:)
      forControlEvents:UIControlEventTouchUpInside];
  [button11 addSubview:button112];
  // 追加1-1-2-1按钮
  UIButton* button1121 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  button1121.frame = CGRectMake( 10, 10, 95, 80 );
  [button1121 setTitle:@"1-1-2-1" forState:UIControlStateNormal];
  [button1121 addTarget:self
              action:@selector(button1121DidPush:)
      forControlEvents:UIControlEventTouchUpInside];
  [button112 addSubview:button1121];
  // 追加1-1-2-2按钮
  UIButton* button1122 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  button1122.frame = CGRectMake( 155, 10, 95, 80 );
  [button1122 setTitle:@"1-1-2-2" forState:UIControlStateNormal];
  [button1122 addTarget:self
              action:@selector(button1122DidPush:)
      forControlEvents:UIControlEventTouchUpInside];
  [button112 addSubview:button1122];
}
#pragma mark ----- Private Methods -----
- (void)button11DidPush:(id)sender {
  [self alertMessage:sender];
}
- (void)button111DidPush:(id)sender {
  [self alertMessage:sender];
}
- (void)button112DidPush:(id)sender {
  [self alertMessage:sender];
}
- (void)button1121DidPush:(id)sender {
  [self alertMessage:sender];
}
- (void)button1122DidPush:(id)sender {
  [self alertMessage:sender];
}
- (void)alertMessage:(UIButton*)button {
  //显示self的标题作为警告框的标题
  NSString* title = [NSString stringWithFormat:@"self = %@", button.titleLabel.text];
  //取得superview的标题
  //当superview非UIButton的情况下，以"UIViewController"替代
  NSString* superViewName;
  if ( [button.superview isKindOfClass:[UIButton class]] ) {
    superViewName = ((UIButton*)button.superview).titleLabel.text;
  } else {
    superViewName = @"UIViewController";
  }
  //取得subviews的标题
  NSMutableString* subviews = [[[NSMutableString alloc] initWithCapacity:64] autorelease];
  [subviews setString:@""];
  for ( id view in button.subviews ) {
    NSString* addString;
    if ( [view isKindOfClass:[UIButton class]] ) {
        //如果子元素为UIButton时，取titleLabel的text属性值
      addString = ((UIButton*)view).titleLabel.text;
    } else if ( [view isKindOfClass:[UILabel class]] ) {
        //如果为UILabel时取其text属性值
      addString = ((UILabel*)view).text;
    } else {
        //上述以外的情况
      addString = [view description];
    }
    if ( [subviews length] > 0 ) {
      [subviews appendString:@", "];
    }
    [subviews appendString:addString];
  }
  NSString* message = [NSString stringWithFormat:@"superview = %@\r\nsubviews = %@",
superViewName, subviews];
  UIAlertView* alert = [[[UIAlertView alloc] initWithTitle:title
                                            message:message
                                            delegate:nil
                                    cancelButtonTitle:nil
                                    otherButtonTitles:@"OK", nil ] autorelease];
  [alert show];
}
- (void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
  [self.navigationController setNavigationBarHidden:NO animated:YES];
}
@end

执行后的效果如图2-24所示。