I need to get only width and height from PNG file. Is it possible to do with UIImage? The reason is because sometimes (in rare cases with some images with odd width and RGB8 format) UIImage returns different dimension than libpng).
I have found an answer here: http://oleb.net/blog/2011/09/accessing-image-properties-without-loading-the-image-into-memory/
#import <ImageIO/ImageIO.h>
NSURL *imageFileURL = [NSURL fileURLWithPath:...];
CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef)imageFileURL, NULL);
if (imageSource == NULL) {
// Error loading image
...
return;
}
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:NO], (NSString *)kCGImageSourceShouldCache,
nil];
CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, (CFDictionaryRef)options);
if (imageProperties) {
NSNumber *width = (NSNumber *)CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelWidth);
NSNumber *height = (NSNumber *)CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelHeight);
NSLog(#"Image dimensions: %# x %# px", width, height);
CFRelease(imageProperties);
}
We can access any metadata from file without loading an image.
Related
Still a bit new and I am having some issues I was hoping someone could help with. I am trying to load a JSON string coming from my server into a collectionview in iOS6
I can pull in the data using a fetchedData method called from the viewDidLoad method and that part works fine. In the fetchedData method, I break out the JSON data and place it in NSDictionaries and NSArrays and can dump the correct data to the log to see it.
The problem is when I try and use any of the information elsewhere in my code such as get the amount of elements in any of hte arrays to use as a counter to fill the collectionview.
It may be that I am tired but I can't seem to get my head around this part. The declaration of many of the main variables was in the fetchedData method and I thought since the were declared there it could be the reason I could not see them elsewhere so I moved the declaration of the variables to the interface section and was hoping this would make the variables GLOBAL and the fetchedData method continues to work just fine, but nowhere else.
When I put in breaks in the cell definition area I can see in the debugger window the variables come up as empty.
I am not sure what sections of the code you may want to see so let me know and I can post them but maybe someone could give an example of how arrays and dictionary items can be accessed in multiple methods.
To avoid confusion and to expose my hodgepodge of code at this point anyway here is the .m file or at least most of it Please don't rip to hard on the coding style I have been trying anything I could think of and tore it up pretty hard myself and it was late.
#import "ICBCollectionViewController.h"
#import "ICBCollectionViewCell.h"
#import "ICBDetailViewController.h"
#interface ICBCollectionViewController () {
NSDictionary* json;
NSDictionary* title;
NSDictionary* shortDescrip;
NSDictionary* longDescrip;
NSDictionary* price;
NSDictionary* path;
NSDictionary* sKU;
NSDictionary* audiotrack;
NSDictionary* audiotracksize;
NSArray* titles;
NSArray* shortDescription;
NSArray* longDescription;
NSArray* prices;
// NSArray* paths;
NSArray* SKUs;
NSArray* audiotracks;
NSArray* audiotracksizes;
}
#end
/*
#interface NSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress;
-(NSData*)toJSON;
#end
#implementation NSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress
{
NSData* data = [NSData dataWithContentsOfURL: [NSURL URLWithString: urlAddress] ];
__autoreleasing NSError* error = nil;
id result = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
if (error != nil) return nil;
return result;
}
-(NSData*)toJSON
{
NSError* error = nil;
id result = [NSJSONSerialization dataWithJSONObject:self options:kNilOptions error:&error];
if (error != nil) return nil;
return result;
}
#end
*/
#implementation ICBCollectionViewController
#synthesize paths;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
dispatch_async(kBgQueue, ^{
NSData* data = [NSData dataWithContentsOfURL: imobURL];
[self performSelectorOnMainThread:#selector(fetchedData:) withObject:data waitUntilDone:YES];
});
// Do any additional setup after loading the view.
}
- (void)fetchedData:(NSData *)responseData {
NSError* error;
//parse out the json data
json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
titles = [json objectForKey:#"title"]; //2
shortDescription = [json objectForKey:#"shortD"];
longDescription = [json objectForKey:#"longD"];
prices = [json objectForKey:#"price"];
self.paths = [json objectForKey:#"path"];
SKUs = [json objectForKey:#"SKU"];
audiotracks = [json objectForKey:#"audiotrack"];
audiotracksizes = [json objectForKey:#"audiotracksize"];
NSLog(#"paths: %#", paths); //3
// NSLog(#"shortDescrip: %#", shortDescription);
NSInteger t=7;
// 1) Get the latest loan
title = [titles objectAtIndex:t];
shortDescrip = [shortDescription objectAtIndex:t];
longDescrip = [longDescription objectAtIndex:t];
price = [prices objectAtIndex:t];
path = [paths objectAtIndex:t];
sKU = [SKUs objectAtIndex:t];
audiotrack = [audiotracks objectAtIndex:t];
audiotracksize = [audiotracksizes objectAtIndex:t];
//NSLog(title.count text);
//NSLog(title.allValues);
// 2) Get the data
NSString* Title = [title objectForKey:#"title"];
NSString* ShortDescrip = [shortDescrip objectForKey:#"shortD"];
NSString* LongDescrip = [longDescrip objectForKey:#"longD"];
NSNumber* Price = [price objectForKey:#"price"];
NSString* Path = [path objectForKey:#"path"];
NSString* SKU = [sKU objectForKey:#"SKU"];
NSString* AudioTrack = [audiotrack objectForKey:#"audiotrack"];
NSNumber* AudioTrackSize = [audiotracksize objectForKey:#"audiotracksize"];
/*************************HERE THE DATA EXISTS*******************************/
/******** Path = "XYXYXYXYXYXY" for example ********************************/
// 3) Set the label appropriately
NSLog([NSString stringWithFormat:#"Here is some data: Title: %# Path %# SKU: %# Price: %# Track %# Size %#",Title, Path, SKU, Price, LongDescrip, AudioTrackSize]);
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
//DetailSegue
if ([segue.identifier isEqualToString:#"DetailSegue"]) {
ICBCollectionViewCell *cell = (ICBCollectionViewCell *)sender;
NSIndexPath *indexPath = [self.collectionView indexPathForCell:cell];
ICBDetailViewController *dvc = (ICBDetailViewController *)[segue destinationViewController];
dvc.img = [UIImage imageNamed:#"MusicPlayerGraphic.png"];
}
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
NSLog(#"paths qty = %d",[paths count]);
return 20;
}
// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *identifier=#"Cell";
ICBCollectionViewCell *cell = (ICBCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
// paths = [json objectForKey:#"path"];
NSDictionary* path = [paths objectAtIndex:indexPath.row];
NSString* Path = [path objectForKey:#"path"];
// NSString* Path = [paths objectAtIndex:indexPath.row];
NSLog(#"%d",indexPath.row);
/***********************HERE IT DOES NOT**************************/
/******** Path = "" **********************************************/
NSLog(#"xxx");
NSLog(path);
NSLog(paths);
NSLog(Path);
NSLog(#"ZZZ");
Path=#"deepsleep";
NSLog(#"xxx");
NSLog(Path);
NSLog(#"ZZZ");
// paths = [json objectForKey:#"path"];
// NSString* Path = [path objectForKey:#"path"];
NSString *imagefile = [NSString stringWithFormat:#"https://imobilize.s3.amazonaws.com/glennharrold/data/%#/mid.png", Path];
NSLog(imagefile);
NSURL *url1=[NSURL URLWithString:imagefile];
dispatch_async(kBgQueue, ^{
NSData *data1 = [NSData dataWithContentsOfURL:url1];
cell.imageView.image =[[UIImage alloc]initWithData:data1];
});
return cell;
}
#end
Try breaking out the JSON data and sorting it in the appDelegate. If you declare public variables there #property (nonatomic, strong) NSDictionary *myDict etc., then you can access those variables by importing your appDelegate and using the following code:
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSDictionary *newDict = appDelegate.myDict;
Otherwise, you can store the information in a singleton, or in the root view controller. The key is to store your variables in a class that won't be deallocated. Most often, it is a bad idea to use a viewController for that purpose-- they have a tendency to be navigated away from, which deallocates the memory and gets rid of your variables. Google "model-view-controller" for more info.
I found out what the main issue was it the ViewDidLoad method I was using a background activity to get the JSON data from my server and as that process was running the foreground was also being processed and since the rest of the code was based on a value returned when the background process finished the data was actually null so all data based on that single piece were also null and it looked as if it was not available. Once I made the process run in the foreground all the variable started having values.
Thanks for your assistance with this
I'm going to create a book shelf in one of my projects. The basic requirements are as follows:
similar to iBooks bookshelf
supports both orientations well
supports all kinds of iOS devices well (different resolutions)
supports deleting and inserting items
supports reordering of items by long press gesture
shows a hidden logo when first row is pulled down
The UICollectionView is the first option that occurred to me. It easily supports grid cells. So I googled it and found some very useful tutorials:
Bryan Hansen's UICollectionView custom layout tutorial
Mark Pospesel's How to Add a Decoration View to a UICollectionView
LXReorderableCollectionViewFlowLayout
And here is the result: (Please ignore the color inconsistency problem because of the graphics I chose are not perfect yet.)
What I did:
Created a custom layout by creating a class inherited from LXReorderableCollectionViewFlowLayout (for reordering purposes) which inherited from UICollectionFlowLayout
Added a decoration view for showing logo
Added a decoration view for showing the bookshelfs
But I ran into a few problems:
1. I can't scroll at all if the items can be shown in one screen
Then I added the following code, to make the contentsize bigger
- (CGSize)collectionViewContentSize
{
return CGSizeMake(self.collectionView.bounds.size.width, self.collectionView.bounds.size.height+100);
}
Then I can scroll now. Here I pull down the first row:
You can see the the decoration view for logo is working.
2. But I got the second set of problems when I pull up the last row:
You can see the decoration view is not added at the green box part.
3. The background of decoration view for bookshelf is getting darker and darker. (Please refer to same problem here
4. The book shelf bar sometimes moves when I reorder the items
I list some of the important code here:
- (void)prepareLayout
{
// call super so flow layout can do all the math for cells, headers, and footers
[super prepareLayout];
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
NSMutableDictionary *shelfLayoutInfo = [NSMutableDictionary dictionary];
// decoration view - emblem
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
UICollectionViewLayoutAttributes *emblemAttributes =
[UICollectionViewLayoutAttributes layoutAttributesForDecorationViewOfKind:[EmblemView kind]
withIndexPath:indexPath];
emblemAttributes.frame = [self frameForEmblem:YES];
dictionary[[EmblemView kind]] = #{indexPath: emblemAttributes};
// Calculate where shelves go in a vertical layout
int sectionCount = [self.collectionView numberOfSections];
CGFloat y = 0;
CGFloat availableWidth = self.collectionViewContentSize.width - (self.sectionInset.left + self.sectionInset.right);
int itemsAcross = floorf((availableWidth + self.minimumInteritemSpacing) / (self.itemSize.width + self.minimumInteritemSpacing));
for (int section = 0; section < sectionCount; section++)
{
y += self.headerReferenceSize.height;
//y += self.sectionInset.top;
int itemCount = [self.collectionView numberOfItemsInSection:section];
int rows = ceilf(itemCount/(float)itemsAcross)+1; // add 2 more empty row which doesn't have any data
for (int row = 0; row < rows; row++)
{
indexPath = [NSIndexPath indexPathForItem:row inSection:section];
shelfLayoutInfo[indexPath] = [NSValue valueWithCGRect:CGRectMake(0,y, self.collectionViewContentSize.width, self.itemSize.height + DECORATION_HEIGHT)];
y += self.itemSize.height;
if (row < rows - 1)
y += self.minimumLineSpacing;
}
y += self.sectionInset.bottom;
y += self.footerReferenceSize.height;
}
dictionary[[ShelfView kind]] = shelfLayoutInfo;
self.shelfLayoutInfo = dictionary;
}
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
NSArray *attributesArrayInRect = [super layoutAttributesForElementsInRect:rect];
// cell layout info
for (BookShelfLayoutAttributes *attribs in attributesArrayInRect)
{
attribs.zIndex = 1;
CATransform3D t = CATransform3DIdentity;
t = CATransform3DTranslate(t, 0, 0, 40);
attribs.transform3D = CATransform3DRotate(t, 15 * M_PI / 180, 1, 0, 0);
}
// Add our decoration views (shelves)
NSMutableDictionary* shelfDictionary = self.shelfLayoutInfo[[ShelfView kind]];
NSMutableArray *newArray = [attributesArrayInRect mutableCopy];
[shelfDictionary enumerateKeysAndObjectsUsingBlock:^(id key, NSValue* obj, BOOL *stop) {
if (CGRectIntersectsRect([obj CGRectValue], rect))
{
UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForDecorationViewOfKind:[ShelfView kind] withIndexPath:key];
attributes.frame = [obj CGRectValue];
NSLog(#"decorationView rect = %#",NSStringFromCGRect(attributes.frame));
attributes.zIndex = 0;
//attributes.alpha = 0.5; // screenshots
[newArray addObject:attributes];
}
}];
attributesArrayInRect = [NSArray arrayWithArray:newArray];
NSMutableDictionary* emblemDictionary = self.shelfLayoutInfo[[EmblemView kind]];
NSMutableArray *newArray2 = [attributesArrayInRect mutableCopy];
[emblemDictionary enumerateKeysAndObjectsUsingBlock:^(NSIndexPath *indexPath, UICollectionViewLayoutAttributes *attributes, BOOL *innerStop) {
if (CGRectIntersectsRect(rect, attributes.frame)) {
[newArray2 addObject:attributes];
}
}];
attributesArrayInRect = [NSArray arrayWithArray:newArray2];
return attributesArrayInRect;
}
I'll appreciate if you're patient enough to read this post and provide any advice or suggestions. And I'll post the complete source code if I can fix all the issues. Thank you in advance.
I would suggest to check your last row and do the [self.collectionView ScrollEnable:NO] same for first row, set background color clear of collectionView and collectionViewCell and that bookshelf image sets on background view.
I have a series of images that I want to make use of in an app. What I wanted to do is store them in an NSArray for easy identification within the drawRect: function.
I have created a .plist file, which details an NSDictionary with the keys simply ascending integer values, and the values corresponding to the image file names. This allows me to iterate through the dictionary and add a series of NSImage objects into the array. I am using a for loop here because the order is important and fast enumeration does not guarantee order of execution when reading from a dictionary!
Currently I am doing the following: (This is in a Subclass of NSView)
#property (strong) NSDictionary *imageNamesDict;
#property (strong) NSMutableArray *imageArray;
...
// in init method:
_imageNamesDict = [[NSDictionary alloc] initWithContentsOfFile:#"imageNames.plist"];
_imageArray = [[NSMutableArray alloc] initWithCapacity:[_imageNamesDict count]];
for (int i=0; i<_imageNamesDict.count; i++) {
NSString *key = [NSString stringWithFormat:#"%d", i];
[_imageArray addObject:[NSImage imageNamed:[_imageNamesDict objectForKey:key]];
}
// When I want to draw a particular image in drawRect:
int imageToDraw = 1;
// Get a pointer to the necessary image:
NSImage *theImage = [_imageArray objectAtIndex:imageToDraw];
// Draw the image
NSRect theRect = NSMakeRect (100,100, 0, 0);
[theImage drawInRect:theRect fromRect:NSZeroRect operation:NSCompositeCopy fraction:1.0];
This all appears to work properly, but with one quirk. I have noticed a small amount of lag that happens in drawing the display, but only when drawing a new image for the first time. Once each image has been seen at least once, I can re-draw any desired image with no lag whatsoever.
Is it that I am not loading the images properly, or is there some way that I can pre-cache each image when I create the objects to add to the for loop?
Thanks!
Assuming you have overcome the "... NSMutableDictionary instead of an NSMutableArray ..." problem pointed out in the comments, you are loading the images properly.
The lag you are describing is because [NSImage imageNamed: ] doesn't do all the work required to draw the image, so that is happening on your first draw.
You could probably get rid of the lag by drawing the images into an offscreen buffer as you add them to your array, something like:
// Create an offscreen buffer to draw in.
newImage = [[NSImage alloc] initWithSize:imageRect.size];
[newImage lockFocus];
for (int i=0; i<_imageNamesDict.count; i++) {
NSString *key = [NSString stringWithFormat:#"%d", i];
NSImage *theImage = [NSImage imageNamed:[_imageNamesDict objectForKey:key]];
[_imageArray addObject: theImage];
[theImage drawInRect:imageRect fromRect:NSZeroRect operation:NSCompositeCopy fraction:1.0];
}
[newImage unlockFocus];
[newImage release];
self.refreshControl.tintColor = [UIColor blueColor];//this just only change it color
Can I change the drop-down Arrow to some picture or another shape? How?
Thanks a lot!
Nope. You can only change the color of the arrow, but not the arrow itself. If you would like to be able to do so, please file an enhancement request and it'll be considered.
Of course, you're also able to write one yourself, or use an open source variant.
Hidden API version (in my actual code, maskImage is a category on UIImage). I don't know if Apple will reject this.
static UIImage *maskImage(UIImage *image, UIColor *color) {
UIImage *retval;
CGRect rect = CGRectMake(0, 0, image.size.width, image.size.height);
UIGraphicsBeginImageContextWithOptions(image.size, NO, image.scale);
[color set];
CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
[image drawAtPoint:CGPointZero blendMode:kCGBlendModeDestinationIn alpha:1];//
retval = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return retval;
}
#protocol UIRefreshHacking <NSObject>
-(UIImageView*)arrow;
#end
#interface UIRefreshControl (GetAtContentView)
-(UIView<UIRefreshHacking>*)_contentView;
#end
#implementation UIRefreshControl (ChangeArrowColor)
-(BOOL)setArrowColor:(UIColor *)arrowColor {
if(![self respondsToSelector:#selector(_contentView)]) {
return NO;
}
UIView<UIRefreshHacking> *cv = [self _contentView];
if(![cv respondsToSelector:#selector(arrow)]) {
return NO;
}
UIImageView *iv = [cv arrow];
iv.image = maskImage(iv.image, arrowColor);
return YES;
}
#end
I am paring a XML and getting an image in Byte form and I have put that in a string. Now I have to draw that image.
I have tried to use various methods but no success. How can I do this?
Try converting the string to NSData:
NSString* str= ....
NSData* data=[str dataUsingEncoding:NSUTF8StringEncoding];
Then take a look at:
UIImage *image = [[UIImage alloc] initWithData:data];
Hope this helps.
You can convert the byte into NSData and then you can get the image using
UIImage *image = [[UIImage alloc] initWithData:data];
OR
UIImage *image = [UIImage imageWithData:data];