If I instantiate a UIImage like this :
UIImage *image = [[UIImage alloc] init];
The object is created but it doesn't contain any image.
How I can check if my object contains an image or not?
You can check if it has any image data.
UIImage* image = [[UIImage alloc] init];
CGImageRef cgref = [image CGImage];
CIImage *cim = [image CIImage];
if (cim == nil && cgref == NULL)
{
NSLog(@"no underlying data");
}
[image release];
let image = UIImage()
let cgref = image.cgImage
let cim = image.ciImage
if cim == nil && cgref == nil {
print("no underlying data")
}
Check for cgImage
or ciImage
, in Swift 3
public extension UIImage {
public var hasContent: Bool {
return cgImage != nil || ciImage != nil
}
}
CGImage: If the UIImage object was initialized using a CIImage object, the value of the property is NULL.
CIImage: If the UIImage object was initialized using a CGImageRef, the value of the property is nil.
检查 CGImageRef 本身是否包含空值意味着 UIImage 对象不包含图像......
This is updated version of @Kreiri, I put in a method and fixed logic error:
- (BOOL)containsImage:(UIImage*)image {
BOOL result = NO;
CGImageRef cgref = [image CGImage];
CIImage *cim = [image CIImage];
if (cim != nil || cgref != NULL) { // contains image
result = YES;
}
return result;
}
An UIImage could only based on CGImageRef or CIImage. If both is nil means there is no image. Example use of giving method:
if (![self containsImage:imageview.image]) {
[self setImageWithYourMethod];
}
hope it will help someone.
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