ios UIImage，检查是否包含图像
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UIImage, check if contain image
提问by Jonathan
If I instantiate a UIImage like this :
如果我像这样实例化 UIImage ：
UIImage *image = [[UIImage alloc] init];
The object is created but it doesn't contain any image.
对象已创建，但不包含任何图像。
How I can check if my object contains an image or not?
如何检查我的对象是否包含图像？
回答by Kreiri
You can check if it has any image data.
您可以检查它是否有任何图像数据。
UIImage* image = [[UIImage alloc] init];
CGImageRef cgref = [image CGImage];
CIImage *cim = [image CIImage];
if (cim == nil && cgref == NULL)
{
NSLog(@"no underlying data");
}
[image release];
Swift Version
迅捷版
let image = UIImage()
let cgref = image.cgImage
let cim = image.ciImage
if cim == nil && cgref == nil {
print("no underlying data")
}
回答by onmyway133
Check for cgImageor ciImage, in Swift 3
在 Swift 3 中检查cgImage或ciImage
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.
CGImage：如果 UIImage 对象是使用 CIImage 对象初始化的，则该属性的值为 NULL。
CIImage：如果 UIImage 对象是使用 CGImageRef 初始化的，则该属性的值为 nil。
回答by mgyky
This is updated version of @Kreiri, I put in a method and fixed logic error:
这是@Kreiri 的更新版本，我输入了一个方法并修复了逻辑错误：
- (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:
UIImage 只能基于 CGImageRef 或 CIImage。如果两者都是 nil 表示没有图像。给予方法的使用示例：
if (![self containsImage:imageview.image]) {
[self setImageWithYourMethod];
}
hope it will help someone.
希望它会帮助某人。
回答by Mahesh Aswathanarayana
Check with CGImageRef with itself wheather it contains null value means UIImage object not contains image.......
检查 CGImageRef 本身是否包含空值意味着 UIImage 对象不包含图像......
