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我有一個相當密集的UITableView，需要稍微優化。問題是，如何使用大中央電臺有效地做到這一點。每個單元格都有一個帶有一對標籤和兩個圖像的UIView。我已經將TableViewCell分類了，並且視圖被重用，儘管當表變大時它仍然有點滯後。我將如何使用GCD來優化表格？還是有更好的方法嗎？我在線程管理方面不是很強大，並且尋求一些建議。iOS GCD用於UITableView
下面是代碼我的tableview：
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
JointCAD *currentCall = [[xmlParser calls] objectAtIndex:indexPath.row];
self.tableView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"texture3.png"]];
TableViewCell *cell = (TableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = [[TableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
cell.callTypeLabel.text = currentCall.currentCallType;
cell.locationLabel.text = currentCall.location;
cell.unitsLabel.text = currentCall.units;
cell.stationLabel.text = [@"Station: " stringByAppendingString:currentCall.station];
cell.selectedBackgroundView = cell.selectionView;
if ([currentCall.callType isEqualToString:@"F"]) {
cell.imageType = Fire;
}
else {
cell.imageType = EMS;
}
if ([currentCall.county isEqualToString:@"W"]) {
cell.imageType1 = Washington;
}
else {
cell.imageType1 = Clackamas;
}
return cell;
}
這裏是子類tableviewcell：
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
callView = [[UIView alloc] initWithFrame:CGRectMake(7.5, 7, 305, 65)];
[callView setAutoresizingMask:UIViewAutoresizingFlexibleLeftMargin |
UIViewAutoresizingFlexibleRightMargin |
UIViewAutoresizingFlexibleWidth];
[callView setContentMode:UIViewContentModeTopLeft];
[callView setBackgroundColor: [UIColor colorWithRed:240.0/255.0 green:240.0/255.0 blue:240.0/255.0 alpha:1.0]];
callView.layer.borderWidth = 1.0;
callView.layer.borderColor = [UIColor colorWithRed:(0/255.0) green:(0/255.0) blue:(0/255.0) alpha:1.0].CGColor;
[self.contentView addSubview:callView];
callTypeLabel = [[UILabel alloc]initWithFrame:CGRectMake(5, 2, 190, 21)];
callTypeLabel.font = [UIFont boldSystemFontOfSize:12.0];
callTypeLabel.textColor = [UIColor blackColor];
callTypeLabel.backgroundColor = [UIColor clearColor];
callTypeLabel.highlightedTextColor = [UIColor whiteColor];
callTypeLabel.adjustsFontSizeToFitWidth = YES;
[callView addSubview:callTypeLabel];
locationLabel = [[UILabel alloc]initWithFrame:CGRectMake(5, 17 , 190, 15)];
locationLabel.font = [UIFont systemFontOfSize:10.0];
locationLabel.textColor = [UIColor blackColor];
locationLabel.backgroundColor = [UIColor clearColor];
locationLabel.highlightedTextColor = [UIColor whiteColor];
locationLabel.adjustsFontSizeToFitWidth = YES;
[callView addSubview:locationLabel];
unitsLabel = [[UILabel alloc]initWithFrame:CGRectMake(4, 43, 190, 21)];
unitsLabel.font = [UIFont systemFontOfSize:10.0];
unitsLabel.textColor = [UIColor blackColor];
unitsLabel.backgroundColor = [UIColor clearColor];
unitsLabel.highlightedTextColor = [UIColor whiteColor];
unitsLabel.adjustsFontSizeToFitWidth = NO;
[callView addSubview:unitsLabel];
stationLabel = [[UILabel alloc]initWithFrame:CGRectMake(195 , 25, 75, 20)];
stationLabel.font = [UIFont systemFontOfSize:12.0];
stationLabel.textColor = [UIColor blackColor];
stationLabel.backgroundColor = [UIColor clearColor];
stationLabel.highlightedTextColor = [UIColor whiteColor];
stationLabel.adjustsFontSizeToFitWidth = YES;
[callView addSubview:stationLabel];
CGRect countyImageFrame = CGRectMake(275, 10, 18, 18);
UIImageView *countyImageView = [[UIImageView alloc] initWithFrame:countyImageFrame];
countyImageView.image = countyImage;
[callView addSubview:countyImageView];
CGRect callTypeImageFrame = CGRectMake(275, 37, 18, 18);
UIImageView *callTypeImageView = [[UIImageView alloc] initWithFrame:callTypeImageFrame];
callTypeImageView.image = callTypeImage;
[callView addSubview:callTypeImageView];
selectionView = [[UIView alloc] initWithFrame:CGRectMake(10, 7, 200, 65)];
[selectionView setBackgroundColor: [UIColor clearColor]];
}
return self;
}
- (void)setImageType:(CallType)newImageType {
imageType = newImageType;
if (imageType == Fire) {
CGRect callTypeImageFrame = CGRectMake(275, 37, 18, 18);
UIImageView *callTypeImageView = [[UIImageView alloc] initWithFrame:callTypeImageFrame];
callTypeImageView.image = [UIImage imageNamed:@"red.png"];
[callView addSubview:callTypeImageView];
}
else if (imageType == EMS) {
CGRect callTypeImageFrame = CGRectMake(275, 37, 18, 18);
UIImageView *callTypeImageView = [[UIImageView alloc] initWithFrame:callTypeImageFrame];
callTypeImageView.image = [UIImage imageNamed:@"yellow.png"];
[callView addSubview:callTypeImageView];
}
}
- (void)setImageType1:(County)newImageType1 {
imageType1 = newImageType1;
if (imageType1 == Washington) {
CGRect callTypeImageFrame = CGRectMake(275, 10, 18, 18);
UIImageView *countyImageView = [[UIImageView alloc] initWithFrame:callTypeImageFrame];
countyImageView.image = [UIImage imageNamed:@"blue.png"];
[callView addSubview:countyImageView];
}
else if (imageType1 == Clackamas) {
CGRect callTypeImageFrame = CGRectMake(275, 10, 18, 18);
UIImageView *countyImageView = [[UIImageView alloc] initWithFrame:callTypeImageFrame];
countyImageView.image = [UIImage imageNamed:@"green.png"];
[callView addSubview:countyImageView];
}
}
是[xmlParser調用]每次解析xml嗎？你的代碼似乎沒有其他任何東西需要線程化。圖像是本地的，操作是標準的。 XML解析是昂貴的，所以這就是爲什麼我想知道。如果是這樣，那麼解析一次並將數組存儲在某個地方，這樣就可以調用objectAtIndex。 – Matt
解析器每次調用刷新時都會運行，方法是拉下表視圖。 XML是動態的，所以它不斷變化，這就是爲什麼用戶有能力刷新。我已經建立了解析器，使用GCD在後臺運行，這有點幫助。解析器僅在刷新方法被調用並且數據存儲在數組中時才運行。我只是擔心這些觀點正在放慢速度。 –
好的，你仍然要確保它每次刷新只解析一次。我沒有從你的迴應中得知這個函數調用是否導致了一個解析操作，但是如果是這樣的話，它將解析表中的任意多個單元格，並且我猜你正在確定[ xmlParser調用] count]。但是，是的，在背景上進行解析是正確的方法。爲了安全起見，您應該在解析發生時顯示某種活動單元格（以防萬一）。在用戶刷新時調用reloadData，並在解析完成時再次調用...但在主線上。 – Matt