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View Code? Open in Web Editor NEWiOS Fast Scrolling with RunLoop Work Distribution
License: MIT License
iOS Fast Scrolling with RunLoop Work Distribution
License: MIT License
使用kCFRunLoopCommonModes替代kCFRunLoopDefaultMode是不是会更好些呢,这样在滚动的时候也能进行加载。还是说有其他我没想到的问题?
@implementation DWURunLoopWorkDistribution
- (instancetype)init
{
if ((self = [super init])) {
_maximumQueueLength = 30;
_tasks = [NSMutableArray array];
_tasksKeys = [NSMutableArray array];
// _timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(_timerFiredMethod:) userInfo:nil repeats:YES];
// 如果不加延迟会导致启动黑屏, 可能是由于启动 App 时, 无法正常 Mode 切换的原因;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.01 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSRunLoop* runLoop = [NSRunLoop currentRunLoop];
[runLoop addPort:[NSMachPort port] forMode:NSDefaultRunLoopMode];
[runLoop run];
});
}
return self;
}
我想问一下:对于这种优化,我们可以看到在tracking模式下,cell上面一片空白(或者你放一个比较小的背景占位图),但是当滑动停止,处于default模式了,这个时候渲染图片了,你会发现之前的空白(或占位图)会被填充,感觉视觉上的效果蛮差的。例如我们希望可以获得微信朋友圈或微博那样的体验,有没有更好的优化方案呢?我们抛开高度缓存这些角度,其他角度怎么优化呢?
我将这个Demo转换成给collectionview 使用,然后从网络上下载图片,发现在上下滚动collectionview的过程中,原本在item = 1位置的图片,变到item = 2的位置,item = 2 的图片变到item = 1 的位置,也就是两个图片互相交换了位置,然后再滑动collectionview的时候又互相交换位置了,一直滚动就一直重复出现这个问题。
为什么我认为,这个不是每次RunLoop结束前执行一次任务,而且在一次RunLoop结束的前下执行了所有在tasks中的任务?
如果只执行一次的话,那么RunLoop休眠,页面保持静止,应该只加载一张图的啊。
while (result == NO && runLoopWorkDistribution.tasks.count) {
DWURunLoopWorkDistributionUnit unit = runLoopWorkDistribution.tasks.firstObject;
result = unit();
[runLoopWorkDistribution.tasks removeObjectAtIndex:0];
[runLoopWorkDistribution.tasksKeys removeObjectAtIndex:0];
}
这个不是一次执行完的吗?
占用内存太大了。
就一个页面,500多M
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如果已进入页面不滑动页面就不会显示图片,
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