SwiftUI ForEach performance

Question

I use 2 foreach loops in my widget body, which slow down the performance (Code completion is slow). Also there are many HStacks and VStacks. Is there a way around this?

  ForEach(0..<data.eventsToday.count)
            {(row) in
                
                if row < 3 {
                    HStack{
                        Rectangle().fill(eventBgColor)
                            .frame(width: 6, height: 25, alignment: .leading)
                            .cornerRadius(3.0)
                        VStack{
                            Text(data.eventsToday[row].title)
                                .font(eventFont)
                                .multilineTextAlignment(.leading)
                                .frame(width: 120.0, height: 14.0, alignment: .bottomLeading)
                                .truncationMode(/*@START_MENU_TOKEN@*/.tail/*@END_MENU_TOKEN@*/).lineLimit(1)
                                .foregroundColor(titleColor)
                            
                            Text("\(String(MediumWidget2GetStartTime(indexRow:row)))")
                                .font(timeFont)
                                .multilineTextAlignment(.leading)
                                .frame(width: 120.0, height: 11.0, alignment: .bottomLeading)
                                .lineLimit(1)
                                .foregroundColor(timeColor)
                        }
                    }.padding(.bottom, 5.0)
                }
            }

Asperi · Accepted Answer · 2020-12-01 10:49:50Z

1

If you want to show just 3 records, then it looks more appropriate to limit data container (and don't iterate all events), like

ForEach(0..<data.eventsToday.prefix(3).count)
    {(row) in
        HStack{
            Rectangle().fill(eventBgColor)
                .frame(width: 6, height: 25, alignment: .leading)
                .cornerRadius(3.0)
            VStack{
                Text(data.eventsToday[row].title)
                    .font(eventFont)
                    .multilineTextAlignment(.leading)
                    .frame(width: 120.0, height: 14.0, alignment: .bottomLeading)
                    .truncationMode(/*@START_MENU_TOKEN@*/.tail/*@END_MENU_TOKEN@*/).lineLimit(1)
                    .foregroundColor(titleColor)
                
                Text("\(String(MediumWidget2GetStartTime(indexRow:row)))")
                    .font(timeFont)
                    .multilineTextAlignment(.leading)
                    .frame(width: 120.0, height: 11.0, alignment: .bottomLeading)
                    .lineLimit(1)
                    .foregroundColor(timeColor)
            }
        }.padding(.bottom, 5.0)
    }

answered Dec 1, 2020 at 10:49

Asperi

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1 Comment

Gibson Neunundsiebzig Over a year ago

Thank you , and for the 2. Foreach i want to start at index 3 to index 6, how would i do that? Like so..? ForEach(3..<data.eventsToday.prefix(3).count). Would It crash if there are less than 4 entries?

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