Navigator-page loading

When the right shift is performed, the negative number is supplemented by 1, the positive number is supplemented by 0, and the sign bit is supplemented; the left shift is supplemented by 0; the shift can be used to take the number. When bit operations are performed, it is best not to use (+-*/) Shell Gg = g alignment command d to exit the program scope: variables defined in composite statements can only be used in composite statements. the attributes, member variables, and methods defined in the M file can only be accessed in the current class, but not open out. // The principle of object-oriented programming: the principle of open and closed, the principle of open and closed, open to internal, closed to external # import "appdelegate. H "# import" fisrtviewcontroller. H "@ interface appdelegate () @ end @ implementation appdelegate-(bool) Application :( uiapplication *) Application didfinishlaunchingwithoptions :( nsdictionary *) launchoptions {self. window = [[uiwindow alloc] initwithframe: [[uiscreen mainscreen] bounds]; // override point for customization after application launch. self. window. backgroundcolor = [uicolor whitecolor]; [self. window makekeyandvisible]; // declare a View Controller to load fisrtviewcontroller * fviewcontroller = [[fisrtviewcontroller alloc] init]; fviewcontroller. view. backgroundcolor = [uicolor bluecolor]; // define a navigator to load the first view controller, that is, with the View Controller uinavigationcontroller * navcontroller = [[uinavigationcontroller alloc] initwithrootviewcontroller: fviewcontroller]; self. window. rootviewcontroller = navcontroller; return yes;} // The implementation file of the first View Controller class # import "fisrtviewcontroller. H "# import" secondviewcontroller. H "@ interface fisrtviewcontroller () @ end @ implementation fisrtviewcontroller-(instancetype) initwithnibname :( nsstring *) bundle :( nsbundle *) handle {self = [Super initwithnibname: Bundle: nibbundleornil]; If (Self) {// custom initialization} return self;}-(void) viewdidload {[Super viewdidload]; // do any additional setup after loading the view. // Add a label and button uilabel * label = [[uilabel alloc] initwithframe: cgrectmake (0, 64,100, 30)] To the View Controller; label. TEXT = @ "I Am a label"; label. textcolor = [uicolor redcolor]; label. backgroundcolor = [uicolor whitecolor]; [self. view addsubview: Label]; uibutton * nextbtn = [uibutton buttonwithtype: uibuttontypecustom]; nextbtn. frame = cgrectmake (220, 64,100, 30); [nextbtn settitle: @ "nextview" forstate: uicontrolstatenormal]; [nextbtn settitlecolor: [uicolor graycolor] forstate: uicontrolstatenormal]; nextbtn. backgroundcolor = [uicolor redcolor]; [nextbtn addtarget: Self action: @ selector (nextdidclik :) forcontrolevents: uicontroleventtouchupinside]; [self. view addsubview: nextbtn]; uiimageview * imageview = [[uiimageview alloc] initwithframe: cgrectmake (30,144,240,296)]; imageview. image = [uiimage imagenamed: @ "1.png"]; [self. view addsubview: imageview];} // when the button is triggered, it is loaded to the second view controller-(void) nextdidclik :( uibutton *) sender {secondviewcontroller * secondviewcontroller = [[secondviewcontroller alloc] init]; secondviewcontroller. view. backgroundcolor = [uicolor yellowcolor]; [self. navigationcontroller pushviewcontroller: secondviewcontroller animated: Yes];} // implementation file of the second view controller class # import "secondviewcontroller. H "@ interface secondviewcontroller () @ end @ implementation secondviewcontroller-(instancetype) initwithnibname :( nsstring *) bundle :( nsbundle *) handle {self = [Super initwithnibname: Bundle: nibbundleornil]; If (Self) {// custom initialization} return self;}-(void) viewdidload {[Super viewdidload]; // do any additional setup after loading the view. uibutton * beforebtn = [uibutton buttonwithtype: uibuttontypecustom]; beforebtn. frame = cgrectmake (0, 64,100, 30); [beforebtn settitle: @ "beforeview" forstate: Unknown]; [beforebtn settitlecolor: [uicolor graycolor] forstate: uicontrolstatenormal]; beforebtn. backgroundcolor = [uicolor redcolor]; [beforebtn addtarget: Self action: @ selector (beforebtn :) forcontrolevents: uicontroleventtouchupinside]; [self. view addsubview: beforebtn];} // when the button is triggered, return to the previous View Controller-(void) beforebtn :( uibutton *) sender {[self. navigationcontroller poptorootviewcontrolleranimated: Yes];}