ios 如何测试空的 UIImageView？
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How to test for an empty UIImageView?
提问by jini
I have the following code where I want to see if a particular UIImageView(image) is set. If not then I want to display an error message.
我有以下代码，我想查看是否设置了特定UIImageView（图像）。如果没有，那么我想显示一条错误消息。
if (image==nil) {
UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"No Image Selected"
delegate:nil
cancelButtonTitle:@"OK"
destructiveButtonTitle:nil
otherButtonTitles:nil];
[actionSheet showInView:[[self view]window]];
[actionSheet autorelease];
}
回答by Wilbur Vandrsmith
… imageView.image == nil? Or, to check for empty images, CGSizeEqualToSize(imageView.image.size, CGSizeZero).
…… imageView.image == nil？或者，要检查空图像，CGSizeEqualToSize(imageView.image.size, CGSizeZero).
回答by MikeJfromVA
It may be tricky to figure out if (UIImageView *)imagehas been initialized with an image. You may want to check the image property:
确定是否(UIImageView *)image已使用图像初始化可能很棘手。您可能需要检查图像属性：
if (image.image == nil)
This will work in the case where image.image==nil(UIImageViewinitialized by image not set) AND in the case where image==nil(since messages sent to nil return nil).
这将适用于image.image==nil（UIImageView由未设置的图像初始化）和image==nil（因为消息发送到 nil return nil）的情况。
Beware local variables as well: Just because you never alloc/initimage doesn't mean it will be nil.
alloc/init也要注意局部变量：仅仅因为你从不成像并不意味着它会为零。
