Question

我似乎无法使系统使用我拥有的自定义创建按钮。我在.m文件的接口部分中有以下声明：

@property (weak, nonatomic) IBOutlet UIButton *useLocationButton;
@property (weak, nonatomic) IBOutlet UIButton *useAddressButton;

然后我的init函数有以下内容

- (id)init
{
if (self = [super initWithNibName:@"TCMDirectionsViewController" bundle:nil]){

    [[self navigationItem] setTitle:@"Get Directions"];

    UIBarButtonItem *cancelItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
                                                                                target:self
                                                                                action:@selector(cancel:)];
    click = NO;
    [[self navigationItem] setLeftBarButtonItem:cancelItem];

    UIImage *buttonImage = [[UIImage imageNamed:@"bluebutton.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(18, 18, 18, 18)];
    UIImage *buttonImageHighlight = [[UIImage imageNamed:@"bluebuttonHighlight.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(18, 18, 18, 18)];

    [[self useLocationButton] setBackgroundImage:buttonImage forState:UIControlStateNormal];
    [[self useLocationButton] setBackgroundImage:buttonImageHighlight forState:UIControlStateHighlighted];
    [[self useAddressButton] setBackgroundImage:buttonImage forState:UIControlStateNormal];
    [[self useAddressButton] setBackgroundImage:buttonImageHighlight forState:UIControlStateHighlighted];
    _locationManager = [[CLLocationManager alloc] init];
    [_locationManager setDelegate:self];
    [_locationManager setDesiredAccuracy:kCLLocationAccuracyNearestTenMeters];
    [_locationManager startUpdatingLocation];
}

return self;
}

当我运行应用程序时，按钮是我在界面构建器中创建的默认白色按钮。

Answer 1

在加载视图之前调用init方法，因此useLocationButton尚不存在。

将您的视图设置放在UIViewController的{{3}}方法中，如下所示：

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIImage *buttonImage = [[UIImage imageNamed:@"bluebutton.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(18, 18, 18, 18)];
    UIImage *buttonImageHighlight = [[UIImage imageNamed:@"bluebuttonHighlight.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(18, 18, 18, 18)];

    [[self useLocationButton] setBackgroundImage:buttonImage forState:UIControlStateNormal];
    [[self useLocationButton] setBackgroundImage:buttonImageHighlight forState:UIControlStateHighlighted];
    [[self useAddressButton] setBackgroundImage:buttonImage forState:UIControlStateNormal];
    [[self useAddressButton] setBackgroundImage:buttonImageHighlight forState:UIControlStateHighlighted];
}

另外，请确保您的IBOutlets实际已连接。您可能希望设置断点以检查引用是否有效。

iOS可以设置UIButton的背景图像

1 个答案: