iOS判断版本

gistfile1.txt

1. iOS版本确认
- (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
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
if (UIGraphicsBeginImageContextWithOptions != NULL) {
    bannerView = [[ADBannerView alloc] init];
    bannerView.delegate = self;
    [self.view addSubview:bannerView];
}