ios - UIImage (UIGraphicsBeginImageContextWithOptions()) 创建速度比使用 PNG 初始化更快吗？

Question

使用此类方法并创建纯色 UIImage 会比创建纯色 png 更快吗？

+ (UIImage*) imageWithColor:(UIColor*)color size:(CGSize)size
{
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
    UIBezierPath* rPath = [UIBezierPath bezierPathWithRect:CGRectMake(0., 0., size.width, size.height)];
    [color setFill];
    [rPath fill];
    UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

想法？

Answer 1

访问磁盘并从缓存中读取 (imageNamed:) 比 Quartz 更快。

-(void) testLoadVSCreate
{
    [self testBlock:^{
        [UIImage imageNamed:@"100x100.png"];
    } times:1000];

    [self testBlock:^{
        [[self class] imageWithColor:[UIColor redColor] size:CGSizeMake(100, 100)];
    } times:1000];
}

-(void) testBlock:(void (^)(void)) block times:(NSUInteger)times {
    double a = CFAbsoluteTimeGetCurrent();
    while (times--) block();
    double b = CFAbsoluteTimeGetCurrent();
    unsigned int m = ((b-a) * 1000.0f);
    NSLog(@"%d ms", m);
}

imageNamed: 似乎在 iPhone 和模拟器上都更快。

2013-05-09 09:47:22.844 Graph[8032:c07] 7 ms
2013-05-09 09:47:22.948 Graph[8032:c07] 101 ms