I have a UISegmentedControl and I have some photos, my initial aim is when ever I click on a particular segment one particular image should appear on the view.
For example: If i have four segments and four images then upon each segment I click I must see a image.
Here I have taken an NSArray and Uploaded all these images using this particular below code:
NSArray * images = [NSArray arrayWithObjects:[UIImage imageNamed:#"f.ppg"], [UIImage imageNamed:#"t.ppg"....etc ], nil];
and after this I want to attach each particular image to a segment index. So here is the code which I wrote.
-(IBAction) segmentActionChanged:(id)sender
{
int segment = mSegment.selectedSegmentIndex;
mImageView.image=[images objectAtIndex:segment];
}
While compiling the application I am not getting any Images displayed and it is quiting abruptly.
Any help regarding this.
To Answer questions 1 and 3 (I think).
to display an image, you will need a UIImageView somewhere. a simple way to do this would be to create an method such as this.
//somewhere in viewDidLoad perhaps?
//title array is an array of strings to use as the label on each section of your control
UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:titleArray];
//this sets the segmentAction: method as the selector for your particular UISegmentedControl
//(so when its value is changed, segmentAction: gets called)
[segmentedControl addTarget:self action:#selector(segmentAction:) forControlEvents:UIControlEventValueChanged];
//the segmentAction: method
- (IBAction) segmentAction:(id)sender
{
//This assumes you have declared the imageView elsewhere, as well as the array and that you
//are using Interface Builder to create/hookup the segmentControl. Basically
myImageView.image = [myImageArray objectAtIndex:sender.selectedSegmentIndex];
}
A few Notes: this does not take advantage of lazy loading, since you are creating and holding all of your images in an array prior to showing them. I would suggest creating an instance variable for the UISegmentedControl so you can access it anywhere also.
Disclaimer: this code is not complete and assumes some initializations.
To answer question number two:A UIImagePickerController is used when dealing with the phone's/devices camera or saved photos album. It is covered in the documentation.
Looks like you're missing a retain.
Related
I am producing a JSON string that I need to parse out and display onto the page. My JSON string outputs information about the contents of a CD like this:
[{"song_name":"Song 1","artist":"John","price":"$1"},
{"song_name":"Song 2","artist":"Anna","price":"$2"},
{"song_name":"Song 3","artist":"Ryan","price":"$3"}]
I would like to display the contents in my viewController in a list format displaying the song_name, artist, and price. I do not want to use a tableView to display this information, but would rather just have a list displayed. How might I go about doing this? I would assume that I need to use NSJSONSerialization, but have only used that for a tableView in the past. Thank you!
In addition to other answers, you can use only one label, just create NSMutableString (for dynamicly adding tracks info) with #"\n" between tracks info, pass it to label.text and set UILabel's property numberOfLines to 0
Follow these steps:
Parse the JSON and store the key-value pair(NSDictionary of CDs) in an NSArray (say infoArray)
Add a UIScrollview as a subview on your viewController's view.
Allocate UILabels dynamically, depending on infoArray count. Looking at your data I believe you can initialize labels with static frames i.e your y can remain static.
Add the text from the infoArray on this label.
Still, I would suggest use UITableView only. It is much simpler and a better approach
You make an array of dictionaries using NSJSONSerialization indeed, then you parse this array one by one and create a view of every dictionary. You're probably best of using a method for this:
-(UIView *) listView: (NSString *)songName andArtist:(NSString *)artist andPrice:(NSString *)price andIndex:(int)viewIndex {
//create your view here and do anything you want
UIView *subView = [[UIView alloc] init] autoRelease];
subView.frame = CGRectMake(0, viewIndex * 70, self.view.frame.width, 70);
//add labels and other stuff
// return the view
return subView;
}
The you add it to the current view by setting different Y values so they appear underneath each other by using the viewIndex of the former method... So if you have an array it goes something like this:
for (int i = 0; i < [array count]; i++) {
NSDictionary *dict = [array objectAtIndex:i];
NSString *songName = [dict valueForKey:#"song_name"];
NSString *artist = [dict valueForKey:#"artist"];
NSString *price = [dict valueForKey:#"price"];
UIView *tempView = [self listView:songName andArtist:artist andPrice:price andIndex:i];
[self.view addSubView:tempView];
}
You have to add it all to a scrollview otherwise you will run into the problem of to many rows on the page. Google for UIScrollView if you don't know how.
But I would recommend against this approach.. Tableviews are there with a reason. They are made for this stuff. Because the also provide for scrolling, drawing and refreshing. If you can, use them!
My question is kind of general; in my project I have 10 UIButton objects
named Button1, Button2, Button3, Button4, Button5, Button6, Button7, Button8, Button9, and Button10
I also have UIImageview That are named exactly like the buttons from 1 to 10.
I want to write a code that will manipulate the image by the last character of the button (always a number from 1 to 10) and will affect the UIImageview the same way
Something like this
buttonlastcharacter = i;
if(sender.lastcharacternumber is:i){
Button%,i.frame = //Some manipulation
But basically all that I want is to have access to a certain object by string
How can I implement such a behavior?
There are a couple of better ways to do this. If these buttons are all static and in IB you can use an IBCollection array for image views and buttons to simply call them up by matching indexes.
Better yet just use the tag value for the buttons or image views.
It is maybe not the ideal solution in your case, but you can do it different ways:
using kvo
UIButton* myButton = [self valueForKey:[NSString stringWithFormat:#"button%i",i]];
or with selectors and properties
UIButton* myButton = [self performSelector:NSSelectorFromString([NSString stringWithFormat:#"button%i",i])];
Hm, you could use an array for your buttons and a tag for your UIImageView objects. They all inherit from UIView, which provides you with a .tag propterty. It is of type NSInteger* .
For convenience reasons I would suggest to name the buttons from 0 to 9. It does not really matter but the first index in the array would be 0 and therefore naming them accordingly just makes things easier.
Define
NSArray *buttonArray;
You may opt for NSMutableArray depending what else you may want to do with it.
In viewDidLoad code:
buttonArray = [NSArray arrayWithCapacity:10];
buttonArray[0] = button0;
..
buttonArray[9] = button9;
In your XIB file in Interface Builder, or whereever you may create the UIImages programmatically, add the tags accordingly.
image0.tag = 0;
...
image0.tag = 9;
assuming you name them image0 to image9.
In your appropriate action method code:
buttonArray[sender.tag] = someManipulation;
You can do it like this,
In your IBAction method:
- (IBAction)click:(id)sender
{
UIButton *but = (UIButton *)sender;
but.frame = your manipulation code;
}
or you can check the title like:
if([but.currentTitle isEqualToString:#"Button1])
{
//Manipulate button 1
}
if you have added tags for the buttons from 1-10 you can use,
if(but.tag == 2)
{
//Manipulate button 2
}
I need to toggle a specific amount of times between two (or maybe later on more) pictures after a button was pressed, and wait a second or two for the change. When a stop-button is pressed at any time, the toggling should stop. My code by now looks like this
IBOutlet UIImageView *exerciseView;
- (void) repetitionCycle {
stopButtonPressed = NO;
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
for (NSInteger counter = kRepetitions; counter >=0; counter--) {
exerciseView.image = [UIImage imageNamed:#"blue.jpg"];
[NSThread sleepForTimeInterval:kSleepDuration];
if (stopButtonPressed) {break;}
image = [UIImage imageNamed:kExerciseEndingPosition];
exerciseView.image = [UIImage imageNamed:#"image1.jpg"];
[NSThread sleepForTimeInterval:kSleepDuration];
if (stopButtonPressed) {break;}
}
self.stopRepetitionCycle;
[pool release];
}
exerciseView is
Besides other things, in stopRepetitionCycle I just set stopButtonPressed to YES, so it stops after it finished the "for" for the first time.
It does count down, it does stop after one cycle, but it doesn't change the picture.
While fiddling around, I set the initial picture via IB, so it finally displayed ANYTHING.. The fun part, when I hit the stop button in the right moment, the second picture is shown. So I guessed I need to set the view manually every time the image should toggle. But
[self.exerciseView addSubview:image];
gives me the error
Incompatible Objective-C types "struct UIImage *", expected "struct UIView *" when passing argument 1 of "addSubview:" from distinct Objective-C type
Also
[self.exerciseView.image addSubview:image];
doesn't do the job and gives me a
UIImage may not respond to addSubview
Any idea what I have to do here?
Thank you very much!
uuhm...
your usage of [NSThread sleep...] puzzles my...
in fact: if you are on a secondary thread (meaning, not the main thread), then you are doing something not allowed, which is trying to access the UI from a secondary thread.
this could explain the strange behavior you are seeing.
on the other hand, if this is the main thread, possibly is not a good idea to call sleep... because that way you will freeze entirely the UI, and you could not possibly intercept the click on the button...
anyhow, what I would suggest, is using NSTimers to move from one image to the next one at certain intervals of time. when the stop button is hidden you would simply cancel the timer and the slideshow would end. pretty clean.
as to the error messages you are having with your image, the fact is that UIImage is not a UIView, so you cannot add it as a subview, but this is not what does not work here...
Use UIImageView. It has built-in support for this.
imageView.animationImages = [NSArray arrayWithObjects:[UIImage imageNamed:#"blue.jpg"], [UIImage imageNamed:#"image1.jpg"], nil];
imageView.animationDuration = kSleepDuration * [imageView.animationImages count];
Wire this function to the start button
- (IBAction) startAnimation {
[imageView startAnimating];
}
and this to the stop button
- (IBAction) stopAnimation {
[imageView stopAnimating];
}
Updating the UI within a loop is almost guaranteed to fail. You should most likely be using an NSTimer to swap the image at a given interval instead.
Furthermore, [self.exerciseView addSubview:image] is failing because you're passing a UIImage and not a UIView. Create a UIImageView (which is a subclass of UIView) with your UIImage and pass that instead.
The method addSubview is used to add only UIViews. You can't use it with a UIImage class. The general syntax is :
[(UIView) addSubview:(UIView*)];
replace
[self.exerciseView addSubview:image];
with
self.exerciseView.image = image;
For the same reason
[self.exerciseView.image addSubview:image];
won't work either.
Im trying to cast a string to a button type. Basically, Im looping through, say 5 buttons, named btn1,btn2..btn5. Here's the snippet:
- (IBAction)replaceImg
{
UIButton* b;
for(int i=0; i<5; i++)
{
b = (UIButton*)[NSString stringWithFormat:#"btn%d",i]; //1!
if([b isHighlighted])
{
int imgNo = (arc4random() % 6) + 1;
UIImage *img = [UIImage imageNamed:[NSStringstringWithFormat:#"%d.png", imgNo]];
[b setImage:img forState:(UIControlState)UIControlStateNormal];
}
}
}
The line marked 1 is giving a problem, if I swap it with b = btn1, it works perfectly. Please help!
I couldnt find a way to access a button by its name either. Like UIImage has something like imageNamed.
you can't cast NSString to UIButton because both are completely different type.
Use tag property of UIView to assign and unique number to each UIButton and at any point of time you could access them by using viewWithTag .
You can't 'cast' an NSString to a button. To get specific buttons, or buttons by name, depends on how you created them. Store your created buttons into an array, or if they come from a NIB then gather their pointers into an array, then loop through the array of button pointers. Controls are also UIViews, so you can assign a numeric 'tag' to each button in Interface Builder then use UIView's viewWithTag: method to search for a specific view with a specific tag.
An NSString isn't a UIButton, so casting it to one isn't going to work. Well, it might work as far as syntax goes, but logic-wise, it will fail. You simply cannot interact with an NSString the same way you can a UIButton. If you need to find your button by name, then you can either retain pointers to those buttons (either in an array, a map, or just as plain instance variables, to name a few ways), or you could alternatively use something like viewWithTag:.
Ok, I have the following very simple animation composed of 25 frames in PNG format. Each frame is 320 × 360 and about 170Kb in size. Here is the code I use
.h:
IBOutlet UIImageView *Animation_Normal_View;
In Interface Builder I have a UIImageView with a referencing outlet pointing to this. All my images are named normal_000_crop.png, normal_001_crop.png, normal_002_crop.png,...
.m:
Animation_Normal = [[NSMutableArray alloc] initWithCapacity:25];
for (int i = 0; i < 25; i++)
{
[Animation_Normal addObject:[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:[NSString stringWithFormat:#"normal_%03d_crop.png", i] ofType:nil]]];
}
Animation_Normal_View.animationImages = Animation_Normal;
Animation_Normal_View.animationDuration = 1; // seconds
Animation_Normal_View.animationRepeatCount = 0; // 0 = loops forever
[Animation_Normal release];
[self.view addSubview:Animation_Normal_View];
[Animation_Normal_View startAnimating];
On the simulator everything loogs good visual animation start as soos as the startAnimating is issued.
But on the iPhone 3G running iOS 4.0.2, the visual animation starts a good 2 to 3 seconds after the startAnimating is issued.
I have tried about every technique on I could find in blogs or forum that should solve this to no avail.
Any hints appreciated even if it's a completly different way to to a PNG based animation.
Thanks.
This is a good question and I will address it here with a few thoughts.
First, you are loading a series of graphics that are around 4MB in total size. This may take a moment, especially on slower (older) devices.
In the #interface block of your .h file you may want to declare two properties such as:
IBOutlet UIImageView *animationViewNormal;
NSMutableArray *animationViewNormalImages;
The first is the UIImageView that you already have (just renamed for best practices) and the second is a mutable array to hold the stack of images for the image view. Let me state that if having "normal" implies state. For clarification, are you loading additional sets of images for different states?
In your .m file in the #interface create the following method:
- (void)loadAnimationImages;
This will provide the function to lead the image stack to the mutable array defined in the header.
In the same .m file in the #implementation you'll want the following:
- (void)loadAnimationImages {
for (NSUInteger i = 0; i < 23; i++) {
NSString *imageName = [NSString stringWithFormat:#"normalCrop%03u", i];
UIImage *image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:imageName ofType:#"png"]];
if (image) {
[animationViewNormalImages addObject:image];
}
}
}
As you can see I renamed the PNG files from normal_%03u_crop to normalCrop%03u as it is best practice to put the index label at the end of the file name (also most apps will output the content this way). The loop loads an image, checks to see that it is an image and then adds the image to the "image stack" in the mutable array.
In the init() you'll need the following:
- (id)init {
...
animationViewNormalImages = [[NSMutableArray alloc] init];
...
}
This allocates the (animationViewNormalImages) mutable array to hold your stack of images for the image view.
We'll now move on to the code for the viewDidLoad():
- (void)viewDidLoad {
[super viewDidLoad];
...
[self loadAnimationImages];
[animationViewNormal setAnimationImages:animationViewNormalImages];
[animationViewNormal setAnimationDuration:1.1f];
[animationViewNormal setAnimationRepeatCount:0]; // 0=infinite loop
...
}
We load the stack of images into the mutable array then set the properties of our imageView with the image stack, duration and repeat count.
Next in the viewDidAppear() we start the image view animating:
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
...
[animationViewNormal startAnimating];
...
}
Once the imageView is animating as an infinite loop we need to handle when leaving the view in the viewWillDisappear():
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
...
[animationViewNormal stopAnimating];
...
}
Last (which should be the second thing we add the .m file) we cleanup in the mutable array in the dealloc():
- (void)dealloc {
...
[animationViewNormalImages release];
[super dealloc];
}
This is how we handle it and works for us, but then again, we're normally not loading 4MB of images into memory to animate.
The .PNG files are compressed when building the app and I am not sure if they are decompressed on the fly when loading the images our of the resource bundle. This is a boolean value int he Build Properties Build Settings (COMPRESS_PNG_FILES).
For performance you may want to consider the following:
Mark opaque views as such:
Compositing a view whose contents are
opaque requires much less effort than
compositing one that is partially
transparent. To make a view opaque,
the contents of the view must not
contain any transparency and the
opaque property of the view must be
set to YES.
Remove alpha channels from opaque PNG
files: If every pixel of a PNG image
is opaque, removing the alpha
channel avoids the need to blend the
layers containing that image. This
simplifies compositing of the image
considerably and improves drawing
performance.
Furthermore, you may find it's better the make one large image with all 24 frames (offset by the width of the individual frame) and then load it once. Then using Core Graphics with CGContextClipToRect then just offset the image context. This means more code but may be faster than using the standard stack method.
Lastly, you may want to consider is converting the .PNG files into .PVR (PVRTC) files. More information can be found here: Apple Tech QA, Apple Docs, and Sample Code.
I hope this helps and please vote it up if it does.
Best,
Kevin
Able Pear Software
imageWithContentsOfFile: tends to take a long time to process, especially if there are lots of files (25 is kind of a lot) and/or they're big.
One thing you can try is to switch it out for imageNamed:, i.e.
[UIImage imageNamed:[NSString stringWithFormat:#"normal_%03d_crop.png", i]]
imageNamed: is generally much faster, but tends to cache images more or less indefinitely.
If loading the images into memory and keeping them around throughout the whole app is unacceptable, you may need to do some tweaky things to load them in at an appropriate time and to unload them after they've been used. That stuff is always tricky, and requires multithreading to not block the main UI while loading. But doable. And there are examples.
Load those images before using the start animating method . I advice an easier way " Just call start animating method in the applicationDidEnterForeground . When calling this one don't forget your UIImageView's alpha property . If you set uiimageiew.alpha=0.01; like this , your start animating method will be called and the user can't see this animation " so there will be no lag anymore.