IOS判断版本

1. iOS版本确认

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- (void)viewDidLoad { [super viewDidLoad]; if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0) { bannerView = [[ADBannerView alloc] init]; bannerView.delegate = self; [self.view addSubview:bannerView]; }

2. 新类是否存在

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Class clazz = NSClassFromString(@"ADBannerView"); if (clazz) { bannerView = [[ADBannerView alloc] init]; bannerView.delegate = self; [self.view addSubview:bannerView]; }

3. 新接口是否存在

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if (UIGraphicsBeginImageContextWithOptions != NULL) { bannerView = [[ADBannerView alloc] init]; bannerView.delegate = self; [self.view addSubview:bannerView]; }