ios - 创建渐变并返回方法

Question

对于有关 iPhone 和 Quartz 编程的菜鸟问题，我们深表歉意。刚刚开始我从 C++ 到 Objective-C 的转换:)

所以，我有这样一个类方法

+(CGGradientRef)CreateGradient:(UIColor*)startColor endColor:(UIColor*)endColor
{
    CGGradientRef result;
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGFloat locations[2] = {0.0f, 1.0f};
    CGFloat startRed, startGreen, startBlue, startAlpha;
    CGFloat endRed, endGreen, endBlue, endAlpha;

    [endColor getRed:&endRed green:&endGreen blue:&endBlue alpha:&endAlpha];
    [startColor getRed:&startRed green:&startGreen blue:&startBlue alpha:&startAlpha];

    CGFloat componnents[8] = {
        startRed, startGreen, startBlue, startAlpha,
        endRed, endGreen, endBlue, endAlpha
    };
    result = CGGradientCreateWithColorComponents(colorSpace, componnents, locations, 2);
    CGColorSpaceRelease(colorSpace);
    return result;
}

及其用法。

-(void)FillGradientRect:(CGRect)area startColor:(UIColor *)startColor endColor:(UIColor *)endColor isVertical:(BOOL)isVertical
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    UIGraphicsPushContext(context);
    CGGradientRef gradient = [Graphics CreateGradient:startColor endColor:endColor];

    CGPoint startPoint, endPoint;
    if (isVertical) {
        startPoint = CGPointMake(CGRectGetMinX(area), area.origin.y);
        endPoint = CGPointMake(startPoint.x, area.origin.y + area.size.height);
    }else{
        startPoint = CGPointMake(0, area.size.height / 2.0f);
        endPoint = CGPointMake(area.size.width, startPoint.y);
    }

    CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);

    CGGradientRelease(gradient);
    UIGraphicsPopContext();
}

一切正常。但是，当我从 Xcode 4 运行分析工具时，我在方法 CreateGradient 中收到有关 result 变量内存泄漏的警告。好吧，我明白那是怎么回事，但在我的调用方法中我释放了渐变对象 (CGGradientRelease(gradient);)。那么，谁错了，如何让分析工具开心呢？

谢谢

Answer 1

由于 CGGradientRef 是 Core Foundation 类型的对象，您可以自动释放它。只需在返回渐变之前添加这一行:

[(id)result autorelease];