I have "n" Arrays with Images and I want to display images correspondingly in "n" sections of tableview using lazy loading concept.I know how to display one array images in table containing one section.Can anyone Help me???
Thanks in Advance
You pretty much do the same thing; but rather than return the number if images as rows in tableView:numberOfRowsInSection and return numberOfSectionsInTableView: as 1 - you turn things around. Have tableView:numberOfRowsInSection return 1 (so one section per image) and numberOfSectionsInTableView: return the number of images.
Your tableView:cellForRowAtIndexPath: code sees the same change; rather than take the index from indexPath.row you take it from indexPath.section.
And that is pretty much it.
Dw.
Just:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [yourImagesArray count];
}
How can we achieve such type of selected values to be changed with mins and secs in UIPickerView???
First, you use the pickerView:viewForRow:inComponent:reusingView: data source method to return the "00" label. This is actually a bit tricky, since pickerview will alter the frame of this view to fill the row. That means you have to embed your properly positioned view inside another view, and then return that container view instead.
As for the labels, those are simply UILabel objects that have been positioned correctly and added as subviews of the pickerview itself.
And to get them to update correctly, just change their titles in the pickerView:didSelectRow:inComponent: method.
This is exactly what UIDatePicker is doing.
You should implement UIPickerViewDelegate Protocol and UIPickerViewDataSource Protocol.
In method - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component just return needful title.
You can also add delegator on valueChanged event of UIPickerView. And each time your value changed you can reload all visible rows and set labels mins and secs at right positions.
Oooor you can just add subview with 2 UILabels over the black line.
Oooor you can add subview with black gradient line with labels mins and secs.
Then using method : - (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component you can set appropriate width of your columns.
I am creating a Unit Converter app using a pickerview with three components and a plist. The first component is category component and the remaining are units components. What i need is when i select an item in category component the remaining two components should get the values regarding that particular component. For this to work how i need to take a plist? Can some one help me on this?
First your que. is not pretty clear, I mean , do u fetching the data using webservice or what...? plist..it is not necessary
all stuff that u've to play with delegates methods for e.g.
1)
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
}
tells how many component u want to add.like categories/unit1/unit2/bla..bla...bla
2)
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger) component
{
}
tells what u hv to do with rows.
3)
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
}
thats it
I don't understand what you mean with the plist... But:
For the context dependent presentation of the two other values you should have a look into pickerView:didSelectRow:inComponent: of UIPickerViewDelegate. There you can react of the change of the value in the first component.
I have a UIPickerView with custom cells. For every moment, I'd like to know which cell is in the center location (behind the tinted selection indicator). The UIPickerView delegate method
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
does provide this information, but only after the picker view has stopped. What I'm looking for is a way to retrieve the currently "selected" cell while the picker view is still spinning and has not yet come to a halt.
As a work around, I've tried to go through KVO and register for each cell's view changes:
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
.
.
[cell addObserver:self forKeyPath:#"frame" options:NSKeyValueObservingOptionOld|NSKeyValueObservingOptionNew context:nil];
}
I do receive callbacks to observeValueForKeyPath:ofObject:change:context:, however no matter whether I scroll the picker view up or down, the received values seem to be always the same:
2011-03-09 08:00:34.429 Project[35069:207] Frame: x=2.00, y=-13.00
2011-03-09 08:00:34.430 Project[35069:207] Location: x=4.00, y=-26.00
2011-03-09 08:00:34.430 Project[35069:207] Change: {
kind = 1;
new = "NSRect: {{2, -13}, {118, 70}}";
old = "NSRect: {{2, -13}, {118, 70}}";
}
2011-03-09 08:00:34.431 Project[35069:207] Frame: x=2.00, y=-13.00
2011-03-09 08:00:34.431 Project[35069:207] Location: x=4.00, y=-26.00
2011-03-09 08:00:34.432 Project[35069:207] Change: {
kind = 1;
new = "NSRect: {{2, -13}, {118, 70}}";
old = "NSRect: {{2, -13}, {118, 70}}";
(Location coordinates are in window frame)
Any other ideas what I could try to get that value?
I think the method:
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view`
with:
[pickerView selectedRowInComponent:0]);
Is exactly what you want.
I think this is interesting. I wanted to do the similar thing with UIPicker, but haven't looked into much yet.
UIDatePicker actually does this, you can drag time around noon and it will toggle AM/PM even though the finger has not lifted from the screen (it should not have called "didSelectRow" yet).
UIDatePicker actually subclasses from UIControl, instead of UIView like UIPickerView. So, UIDatePicker is probably observing all UIControlEvents to do this.
Observing -pickerView:titleForRow:forComponent probably works for now, but if behavior changes later (ie caching behavior, ie) is changed, this will break...
One suggestion is to try KVO on center property, instead of frame.
Edit1: By the way, how does your observeValueForKeyPath method look like?
Edit2: Upon further research, it seems most of UIKit is not KVO compliant.
See this answer -
Key value Observing during UIView Animations
So, it seems like only option is to keep poling for the view's value when it's visible. How about forloop and pole frame/center property whenever it's in view?
You can use your picker delegate's -pickerView:titleForRow:forComponent: method to give you a pretty good idea of where the picker's wheel is. As you scroll in one direction or the other, the picker will ask its delegate for the title (or view) for a row. The number of rows between the "center" of the wheel and the row the picker is asking for depends on the row height, but you'll likely know what that is.
You'll have to experiment a bit to get it right. The picker seems to ask for one or two rows that aren't yet visible, perhaps to keep the scrolling smooth. In my test with a picker that displays 5 rows, there seems to be about a 3-row difference between the row the picker was asking for and the center. You'll obviously also have to keep track of the direction of rotation (up or down), and you won't find out if the first or last two or three rows are selected until your -pickerView:didSelectRow:inComponent: is called.
Just a quick thought, but you could add a UIScrollView (transparent with a contentView that is as tall as the number of components.) over the UIPickerView.
Then listen to the UIScrollViewDelegate methods to get the live scrolling data you need.
The tricky part would be passing along the touch events from the scroller to the picker so that it would act as expected.
The problem you have with UIPickerView is that the view you are setting for the cells are actually subViews.
UIPickerView is built from various imageViews, a TableView and a selection line.
The view you provide when using viewForRow are inserted as subViews of the tableView's cells and so their frame is never changed.
The only frame that changes is the frame of the actual tableView cell, to which of course you have no access.
A possible solution is to simply replace the UIPickerView's tableView with your own.
You can do this by setting the number of rows for the UIPickerView to be 0, and place a transparent tableView over the UIPickerView. Your tableView will hold the actual cells, and since a UITableView inherits from UIScrollView, you can get events about the scroll and simply check which UITableViewCell is currently under the selection line.
The frame does not change because the cell is not moving. One of its superviews is, and the cell is carried along with it. To figure out the cell's coordinate in the parent UIPickerView, try this:
CGRect theApparentRect = [theCell convertRect: theCell.bounds toView: thePicker];
The resultant rectangle will be in the coordinate system of thePicker, and you can then figure out if it's in the middle with the following simple test:
CGPoint middleOfThePicker = CGPointMake
(
CGRectGetMidX(thePicker.bounds),
CGRectGetMidY(thePicker.bounds)
);
Boolean isInMiddle = CGRectContainsPoint(theApparentRect, middleOfThePicker);
How can i disable UIPickerView column?
I want to disable only one column of picker. Lets say i have picker with 3 column and i want to disable second column.
There are a couple options here.
1) Capture interaction with the second column and override it.
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;
This method can be implemented to simply go back to where it was before the selection. However, they will still be able to interact with the second column.
2) Simply remove the column from the picker.
I believe this is the best option. Have some boolean 'showSecondColumn'. Then, in:
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
you can simply check your little flag and return the appropriate number. UIPickerView has a method: reloadAllComponents
Good luck!
It seems there is no way to disable column. I solved(not best solution) like this:
get column as "image" (snapshot)
grayscale "image"
set "image view" user interaction enabled
add "image view" to picker as subview
If there is any better way it would be great.