ViewController.m

#import "ViewController.h"#import "DJOneViewController.h"#import "DJTwoViewController.h"#import "DJThreeViewController.h"@interface ViewController ()@property (nonatomic,strong) DJOneViewController *vc1;@property (nonatomic,strong) DJTwoViewController *vc2;@property (nonatomic,strong) DJThreeViewController *vc3;- (IBAction)btn1Click;- (IBAction)btn2Click;- (IBAction)btn3Click;@end@implementation ViewController- (DJOneViewController *)vc1 {    if (!_vc1) {        DJOneViewController *vc = [[DJOneViewController alloc] init];        vc.view.frame = CGRectMake(60, 0, 600, 300);        self.vc1 = vc;    }    return _vc1;}- (DJTwoViewController *)vc2 {    if (!_vc2) {        DJTwoViewController *vc = [[DJTwoViewController alloc] init];        vc.view.frame = CGRectMake(60, 0, 600, 320);        self.vc2 = vc;    }    return _vc2;}- (DJThreeViewController *)vc3 {    if (!_vc3) {        DJThreeViewController *vc = [[DJThreeViewController alloc] init];        vc.view.frame = CGRectMake(60, 0, 600, 320);        self.vc3 = vc;    }    return _vc3;}- (void)viewDidLoad {    [super viewDidLoad];    }- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}- (IBAction)btn1Click {    [self.vc2.view removeFromSuperview];    [self.vc3.view removeFromSuperview];        [self.view addSubview:self.vc1.view];}- (IBAction)btn2Click {    [self.vc1.view removeFromSuperview];    [self.vc3.view removeFromSuperview];    [self.view addSubview:self.vc2.view];        }- (IBAction)btn3Click {    [self.vc1.view removeFromSuperview];    [self.vc2.view removeFromSuperview];    [self.view addSubview:self.vc3.view];}@end

 

最终效果：