的UIImage，檢查是否含有圖像

Question

如果我實例化這樣一個UIImage：

UIImage *image = [[UIImage alloc] init]; 

對象被創建，但它不包含任何圖像。

我如何檢查我的對象是否包含圖像？

Answer 1

您可以檢查它是否有任何圖像數據。

UIImage* image = [[UIImage alloc] init]; 

CGImageRef cgref = [image CGImage]; 
CIImage *cim = [image CIImage]; 

if (cim == nil && cgref == NULL) 
{ 
    NSLog(@"no underlying data"); 
} 
[image release]; 

Answer 2

檢查與CGImageRef與自身wheather它包含空值意味着UIImage對象不包含圖像.......

Answer 3

檢查cgImage或ciImage，在夫特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.

Answer 4

這是@Kreiri的更新版本，我提出了一種方法和固定的邏輯錯誤：

- (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; 
} 

UIImage只能基於CGImageRef或CIImage。如果兩者都是零意味着沒有圖像。舉例使用賦予方法：

if (![self containsImage:imageview.image]) { 
    [self setImageWithYourMethod]; 
} 

希望它能幫助別人。