ios6/io7 画面适配



                              iOS7下view默认是全屏模式，与iOS6有很大的不同，这样view的坐标值与以前不一样了，如果程序中有Navigation Bar，    以前是从Navigation Bar底部开始计算y值的，现在却是从Status Bar开始计算y值。       对此，苹果公司给出了如下解决方案：            - (void)viewDidLoad              {                  if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) {                self.edgesForExtendedLayout = UIRectEdgeNone;             }               }              现在坐标就是开始从Navigation Bar开始计算了。然而这种情况只适合在Navigation Bar的情况，如果没有Navigation Bar,     坐标仍然是从Status Bar顶部开始计算的。           如果底部有Tab Bar的情况呢，如果要兼容以前的frame设置，那么就需要设置UIViewController的edgesForExtendedLayout为UIRectEdgeNone。                 如果我们的代码没有用storyboard, 没有用xib,纯代码的情况，如果要适配iOS7，那么上面只是介绍了有Navigation Bar, Tool Bar的情况，  如果只是单纯的View,那么我们的代码运行在iOS7上，会有向上20px偏移，这需要手动修改：       if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) {             self.view.bounds = CGRectMake(0, -20, self.view.frame.size.width, self.view.frame.size.height );       }                             上面的方法需要对所有的UIViewController进行设置，比较麻烦，还有一种较为简单的方法，就是设置window，这样可以影响所有的subview   if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) {             [application setStatusBarStyle:UIStatusBarStyleLightContent];             self.window.clipsToBounds =YES;               self.window.frame =  CGRectMake(0,20,self.window.frame.size.width,self.window.frame.size.height-20);         self.window.bounds = CGRectMake(0, 20, self.window.frame.size.width, self.window.frame.size.height);      }              不过这种方法有问题，当屏幕旋转时，Status Bar位置将不动。所以不推荐用这种方法，       可以写一个UIViewController的category方法，然后调用方法一中的代码。这样对全工程进行修改以适配iOS7.                                   使用xib进行布局                            新建一个UIViewController的子类，叫TestViewController，选中创建xib文件。        然后在AppDelegate中将window的rootViewController换成我们新建的TestViewController实例      现在我们在xib中拖入一个button，frame为(177, 0, 73, 44)                                                                                                                                                                                                                                                                                                                     由于iOS7中扁平化设计了，button没有了边框，等一下我们会用xcode5+ios7来运行本程序，为了更清楚的看清frame，    在此将button的边框显示出来，然后关连一个UIButton的变量textBtn到代码中,并用代码再生成一个button                     _testBtn.layer.borderWidth = 1;             UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];         btn.frame = CGRectMake(0, 0, 100, 44);            btn.layer.cornerRadius = 0;             btn.layer.borderColor = [UIColor blackColor].CGColor;           btn.layer.borderWidth = 1;             [btn setTitle:@"Test" forState:UIControlStateNormal];           [self.view addSubview:btn];            运行程序，效果如图                                                                                                                                                                                                                                                                                                                                                      然后用xcode5打开用iOS7的效果：                                                                                                                                                                                                                                                                                                                                                                                   对比可以看出，iOS7是全屏的模式。 这样一来，从iOS6中升级过来的程序，布局就不正确了，有20px的偏移，     上面介绍了用代码解决的方法，在这儿我们先用代码的方法来试试，在viewWillAppear中加入以下代码：      if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) {             self.view.bounds = CGRectMake(0, -20, self.view.frame.size.width, self.view.frame.size.height );       }              再运行程序，效果如下：                                                                                                                                                                                                                                                                                                                                                      其中代码加入的button，下移了20px, 可是xib中拖入的button还是以status bar顶部y＝0开始计算frame.这可能是由于用到了auto layout,   所以xib有自己的frame计算方式. 代码生成的没有用auto layout约束，则受到了上面代码的影响。我们禁用xib的autolayout试试，再运行：                                                                                                                                                                                                                                                                                                                                                                          这下由于没有auto layout的作用，都开始从status bar下面开始计算frame了。                       如果程序中的view全是xib，没有用代码生成，那么还有一种解决方法，条件是xib中没有开启autolayout，而且不用代码控制self.view.bounds  然后在在xcode5中选择我们的xib，并选择view中拖入的button，选择它的Size inspector,如图：                                                                                                                                                                                                                                                                                                                                                对比一下就会发现，右边较之前版本多了一些内容，多了一个ios6/ios7 Deltas.它就是用来做iOS6的xib适配到iOS7用的。    由于iOS7中，全屏的模式，所以需要设置＋20,这样才从status bar底部开始显示。现在将button的y值设为20.如图：                                                                                                                                                                                                                                             xcode5+ios7运行效果如图：                                                                                                                                                                                                                                                                                    由于它的frame是从20开始的，细心的读者可能会有疑问了，如果我们运行在iOS7以前的设备上，由于frame是从20开始的，不是我们想要的效果。 是从status bar下面20px.                           现在我们在将Deltas中y值设为-20.再运行到iOS6的设备上，效果如下：                                                                                                                                                                                                                                                                                            以上是在非autolayout模式下适配iOS7，下面来介绍一下autolayout下的适配工作。                      我们用xcode4.6.3创建一个simgle view application. 选中Use storyboard.        拖一个UIButton到view中。 由于开启了autoLayout， 在xcode4.6.3中，自动会有两个auto layout约束，分别是水平与垂直的约束：                                                                                 运行程序效果：                                                                                                                                                                                                                                                                                              可以看到是垂直方向上距status bar底部是45px，距右边是186px.                        现在我们用xcode5打开这个工程。会提示Upgrade storyboard，我们点击Upgrade. Upgrade后，会发现，垂直方向上有变化了，   约束是从顶部开始，不是从status bar底部开始计算。这和我们想要的结果不一样，我们还是希望约束是从status bar底部开始计算。                  仔细看看storyboard中的View Controller，会发现多了两项内容，分别是Top Layout Guide，Bottom Layout Guide.                                                                                                     现在选中button,按住control键，然后拖到Top Layout Guide上，在弹出的对话框选择Vertical spacing                                                                                                            这样又建立了一个垂直约束，你会发现这个约束是从Status bar底部开始计算的。这个约束有点像是我们需要的，                                                                                     但是这个约束距status bar是25px,我们想要的是45px. 那只需要修改一下，将25px改为45px，你会发现有storyboard中有红色提示，   这说明约束条件发生了冲突，因为垂直约束的值都为45，显示冲突了。                                                                                                                                                                                                                                                                                                    由于我们只需要status bar底部开始计算的那个约束，所以我们将旧的那个删掉即可。                                                                                                       现在分别选择iOS6/iOS7来运行。都是距status bar下面45px显示button. 适配工程完成。                                                                                  更多自动布局auto layout参考 http://www.cocoachina.com/applenews/devnews/2013/1203/7462.html