How to dynamically adjust method names and calls with Objective-C - iphone

I am trying to condense my code for a method and was wondering how I would achieve the following:
I have a bunch of variables that differ only in their number such as:
int intVariable1
int intVariable2
UILabel Label1
UILabel Label2
BOOL bool1
BOOL bool2
etc.
So I want to call a method and pass in an int. That int would determine which ints, UILablels, and BOOLs get worked on. So if a 1 was passed in the method would work on these variables like this:
- (void) DyanamicMethod: (int) inputNumber {
//something that uses the inputNumber to act on the 1 variables
intVariable1 = someValue;
[Label1 setText:someText];
bool1 = YES;
}
Obviously if a 2 were passed in I would want the variables to be of the 2 type. I'm assuming you would do something with creating a string somehow, but I'm not sure how to adjust that to use it to become a variable name. Any insight would be appreciated. Thank you for your time.

Declare the variables as arrays:
int intVariable[2];
UILabel *Label[2];
BOOL bools[2];
Then the method would look like this:
intVariable[inputNumber] = someValue;
[Label[inputNumber] setText:#"someText"];
bools[inputNumber] = YES;
Keep in mind that array indexes are zero-based so in the arrays above, variable "1" is at index 0 and variable "2" is at index 1. Your method could also just take the inputNumber and subtract one from it to get the array index.

You can use key-value coding.
- (void) DyanamicMethod: (int) inputNumber {
//something that uses the inputNumber to act on the 1 variables
NSString* key = [NSString stingWithFormat:#"Label%i", number];
UILabel* label = [self valueForKey:key];
label.text = newString;
}

If you needed something like that you could keep an NSArray of all of the labels ...
Like
in the class interface section:
NSArray* labels ;
In init:(or loadView)
labels = [[NSArray alloc] initWithObjects:Label1, Label2,etc] ;
In dealloc:
[labels release] ;
in DyanamicMethod: (int) inputNumber
UILabel* label = [labels objectAtIndex:inputNumber] ;
Repeat for each type ... Or make a new class holding the label, int and the bool, and have the array be of that type.
Another way might be:
Make properties for each of your member variables.
Then in your function:
UILabel label1 = [self performSelector:sel_getUid([[NSString stringWithFormat:#"label%d", inputNumber] UTF8String])] ;
I think using an array of some sort is better for this situation, but its possible to do it this way. See NSObject Documentation for performSelector.

You could do this with properties (well, you don't NEED properties, but they'd make it simpler), though you'd have to switch to objects:
#property (nonatomic, readwrite, retain) NSNumber *variable1, *variable2;
#property (nonatomic, readwrite, retain) NSNumber *bool1, *bool2;
#property (nonatomic, readwrite, retain) UILabel *label1, *label2;
- (void) DyanamicMethod: (int) inputNumber {
[[self valueForKey: [NSString stringWithFormat: #"label%d", inputNumber] setText: someText];
[self setValue: [NSNumber numberWithInt: inputNumber]
forKey: [NSString stringWithFormat: #"variable%d", inputNumber]];
[self setValue: [NSNumber numberWithBool: YES]
forKey: [NSString stringWithFormat: #"bool%d", inputNumber]];
}

Do you have too many variables for a simple switch statement?
switch(inputNumber) {
case 1:
intVariable1 = someValue;
[Label1 setText:someText];
bool1 = YES;
break;
case 2:
intVariable2 = someValue;
[Label2 setText:someText];
bool2 = YES;
break;
// etc
}

Related

Assign string to UIButton's tag value

I wanted to give a string value to UIButton tag for unique identities.
I tried this code.But it doesnt work.
NSString *A;
NSString *B;
NSString *C;
NSString *D;
firstOptionABtn.tag=[A integerValue];
secondOptonBbtn.tag=[B integerValue];
thirdOptionCbtn.tag=[C integerValue];
fourthOptionDbtn.tag=[D integerValue];
- (IBAction)BtnClicked:(UIButton *)sender {
NSLog(#"%ld",(long)sender.tag);
}
I don't like this way but it will print 0 every time. Where am I going wrong?
Please help. Thanks
It returns zero as you did not initialize string, and it has null value when you convert it into integer it returns you zero. And it seems that you create your button from NIB so you can set their tag value from there and then get there value by implementing.
-( IBAction )buttonClicked:(id)sender
{
UIButton *btn= (UIButton *)sender;
NSLog(#"%d",btn.tag);
}
but if u want the output A,B,C, D then there is also a way
-(void)viewDidLoad{
btn1.accessibilityLabel=#"A";
btn2.accessibilityLabel=#"B";
btn3.accessibilityLabel=#"C";
btn4.accessibilityLabel=#"D";
}
-(IBAction)buttonClicked:(id)sender {
UIButton *btn= (UIButton *)sender;
NSLog(#"%#",btn.accessibilityLabel);
}
output is A, B, C, D
What need to use string for set tag value of button... why not set tag of Button statically simply set like :-
firstOptionABtn.tag=1;
First time seen this setting tag with string to int convert
In your queston First is you are not seting the value of you string
NSString *A;
NSString * B;
NSString * C;
NSString * D;
if you set value of string like
A=#"2"
then your code working and you got the value at the button click event
firstOptionABtn.tag=[A integerValue];
its output is
sender tag 2
Into you String value consider any Number value then the covert string to Intiger cosider only Number not alphabet character like
for example
If you set value of string like A=#"2aaabbb" then the output of button tag is 2 But if you set string value like A=#"bb2aaabbb" then output of button tag is Always 0 consider.
UPDATE
if you wish to set character to int
you can convert NSString to ASCII Like Bellow
A=#"A"
int ASCIINumber = [A characterAtIndex:0];
button.tag=ASCIINumber;
OUTPUT IS:- 65 for Upper case if lower case OUTPUT IS 97
But as using above method i suggest to you use simply set tag=intNumber instead of doing above.
It's not possible dear to set string in tag. Tag only takes int value as you said you know.
Create a custom view which is composed of UIButton and a NSString property or an ivar which will serve as tag.
#interface MyButton: UIView
#property(nonatomic, strong) UIButton *button;
#property(nonatomic, strong) NSString *uniqueTag;
#end
Hope that helps!
we can make a category for tag string in UIButton.
#interface UIButton (setTag)
#property(nonatomic, retain) NSString *tagString;
#end
And any where in your file you can set the tag string to your UIButton.
e.g
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[btn setTagString:#"Hello"];
you can always create a custom class containing a string property to go along with said classes
for example : create a custom class for UIButton
and then at the Header File put :
#property (nonatomic, strong)NSString *labelTag;
- (id)initWithFrame:(CGRect)frame withLabelTag:(NSString *)str;
and then, at the implementation create a super method of init with frame so it looked like this :
- (id)initWithFrame:(CGRect)frame withLabelTag:(NSString *)str{
self = [super initWithFrame:frame];
if (self) {
//Init code
_labelTag = str;
}
return self;
}
after that, whenever you want to set or call the string tag of the button you only need to declare it and call it like this :
MyCustomButton *button = [[MyCustomButton alloc]initWithFrame:frame withLabelTag:#"this is the title"];
//and to call it :
NSLog (#"the button's tag is :%#", button.labelTag)
or, you could always just use the button's title property and if you don't want it to show on your button, just set its HIDDEN prop to YES
There are two scenarios.
Case 1: If your tag string contains only numbers - (Eg: tagStringValue = "1433")
Use myButton.tag = [tagStringValue intValue];
Get back the button using
UIButton *myButton = ([[self.view viewWithTag:[tagStringValue intValue]] isKindOfClass:[UIButton class]])?(UIButton *)[self.view viewWithTag:[tagStringValue intValue]]:nil;
Case 2: If your tag string contains numbers and strings - (Eg: tagStringValue = "ss1433kk")
Subclass the UIButton and add a property like:
#property (nonatomic, strong) NSString *stringTag; and use this instead of default Tag.

How to store not id type variable use a objc_getAssociatedObject/objc_setAssociatedObject?

I use a category, and some variable stored in a UIView.
but only stored id type, so I really want none id type (int, float, double, char... and so on)
How to write a code?
#import <UIKit/UIKit.h>
#import <objc/runtime.h>
#interface UIView (CountClip)
#property (nonatomic, copy) NSString *stringTag;
#property (nonatomic) float offsetY;
#end
#import "UIView+CountClip.h"
#implementation UIView (CountClip)
static NSString *kStringTagKey = #"StringTagKey";
- (NSString *)stringTag
{
return (NSString *)objc_getAssociatedObject(self, kStringTagKey);
}
- (void)setStringTag:(NSString *)stringTag
{
objc_setAssociatedObject(self, kStringTagKey, stringTag, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (float)offsetY
{
// how to write a correct code?
return objc_getAssociatedObject(self, <#what is a code?#>);
}
- (void)setOffsetY:(float)offsetY
{
// how to write a correct code?
objc_setAssociatedObject(self, <#what is a code?#>,...);
}
#end
You need to convert floats to NSNumber instances and vice versa:
static NSString *kOffsetYTagKey = #"OffsetYTagKey";
- (float)offsetY
{
// Retrieve NSNumber object associated with self and convert to float value
return [objc_getAssociatedObject(self, kOffsetYTagKey) floatValue];
}
- (void)setOffsetY:(float)offsetY
{
// Convert float value to NSNumber object and associate with self
objc_setAssociatedObject(self, kOffsetYTagKey, [NSNumber numberWithFloat:offsetY], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
To store variables such as CGPoint, CGRect or CGSize, have a look at NSValue class and use appropriate method:
NSValue *value;
value = [NSValue valueWithCGPoint:point];
value = [NSValue valueWithCGRect:rect];
value = [NSValue valueWithCGSize:size];
Then convert it back via:
NSValue *value = ...;
CGPoint point = value.CGPointValue;
CGRect rect = value.CGRectValue;
CGSize size = value.CGSizeValue;
FYI:
A much faster way of setting and getting associated objects could be this:
objc_setAssociatedObject(self, #selector(stringTag), stringTag, OBJC_ASSOCIATION_COPY_NONATOMIC);
objc_getAssociatedObject(self, #selector(stringTag));
This way you don't have to create the kStringTagKey variable.

Problem with allocating memory for an Objective-C data object

I've been programming objective-C for a few months now and have done pretty well so far without having to post any questions. This would be my first. The problem is that I'm getting a memory leak warning from a data object in one of it's methods. I can see that the problem is that I'm sending an alloc to it without releasing it, but I don't know how else to get it to retain the object in memory. If I take the alloc out, the program crashes. If I leave it in, it leaks memory. Here is the method in question:
+ (id) featureWithID:(int)fID name:(NSString*)fName secure:(int)fSecure {
Feature *newFeature = [[self alloc] init];
newFeature.featureID = fID;
newFeature.featureName = fName;
newFeature.featureSecure = fSecure;
return [newFeature autorelease];
}
This method is called by another method in my view controller. This method is as follows:
+ (NSMutableArray*) createFeatureArray {
NSString *sqlString = #"select id, name, secure from features";
NSString *file = [[NSBundle mainBundle] pathForResource:#"productname" ofType:#"db"];
sqlite3 *database = NULL;
NSMutableArray *returnArray = [NSMutableArray array];
if(sqlite3_open([file UTF8String], &database) == SQLITE_OK) {
const char *sqlStatement = [sqlString UTF8String];
sqlite3_stmt *compiledStatement;
if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {
while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
Feature *myFeature = [Feature featureWithID:sqlite3_column_int(compiledStatement,0)
name:[NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)]
secure:sqlite3_column_int(compiledStatement,2)];
[returnArray addObject:myFeature];
}
}
// Release the compiled statement from memory
sqlite3_finalize(compiledStatement);
}
sqlite3_close(database);
return returnArray;
}
I have tried several things, such as creating a featureWithFeature class method, which would allow me to alloc init the feature in the calling method, but that crashed the program also.
Please let me know if you need any clarification or any other parts of the code. Thank you in advance for your help.
UPDATE: 4/14/2011
After reading the first two responses I implemented the suggestion and found that the program is now crashing. I am at a complete loss as to how to track down the culprit. Hoping this helps, I am posting the calling method from the view controller as well:
- (void)setUpNavigationButtons {
// get array of features from feature data controller object
NSArray *featureArray = [FeatureController createFeatureArray];
int i = 0;
for (i = 0; i < [featureArray count]; i++) {
Feature *myFeature = [featureArray objectAtIndex:i];
CGRect buttonRect = [self makeFeatureButtonFrame:[featureArray count] withMember:i];
UIButton *aButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[aButton setFrame:buttonRect];
[aButton addTarget:self action:#selector(buttonTouched:) forControlEvents:UIControlEventTouchUpInside];
[aButton setTitle:[NSString stringWithFormat:#"%#",myFeature.featureName] forState:UIControlStateNormal];
aButton.tag = myFeature.featureID;
[self.view addSubview:aButton];
}
}
NOTE: These methods are posted in reverse of the order they are invoked. This last method calls the second method, which in turn, calls the first.
UPDATE: I've updated these functions to show what is in there now: Below, I will post the header files for the object - maybe that will help
#interface Feature : NSObject {
int featureID;
int featureSecure;
NSString *featureName;
}
#property (nonatomic, assign) int featureID;
#property (nonatomic, assign) int featureSecure;
#property (nonatomic, retain) NSString *featureName;
- (id) init;
- (void) dealloc;
+ (id) featureWithID:(int)fID name:(NSString*)fName secure:(int)fSecure;
#end
#interface FeatureController : NSObject {
}
- (id) init;
- (void) dealloc;
+ (NSMutableArray*) createFeatureArray;
+ (Feature*) getFeatureWithID:(int)fetchID;
#end
Convenience methods should follow the convention of returning autoreleased objects. Change this:
+ (id) featureWithID:(int)fID name:(NSString*)fName secure:(int)fSecure {
Feature *newFeature = [[self alloc] init];
...
return newFeature;
}
to:
+ (id) featureWithID:(int)fID name:(NSString*)fName secure:(int)fSecure {
Feature *newFeature = [[self alloc] init];
...
return [newFeature autorelease];
}
The name of your method - +featureWithID:name:secure: - indicates that it returns an object that the caller does not own. Instead, it is returning an object that has been retained, that the caller therefore owns and must release. To fix this (and your leak), simply replace return newFeature with return [newFeature autorelease].
There's nothing more you need to do, because your own code doesn't need a long-lasting ownership claim, and the array to which you're adding the object will manage its own ownership claim over it.
In +createFeatureArray, you’re over releasing the array:
+ (NSMutableArray*) createFeatureArray {
…
NSMutableArray *returnArray = [[[NSMutableArray alloc] init] autorelease];
…
return [returnArray autorelease];
}
In the first line, you used +alloc, so you own the array. Then you used -autorelease, so you do not own the array any more. This means that you shouldn’t send -release or -autorelease to it, which you are doing in the return line.
You can fix that by changing those lines to:
+ (NSMutableArray*) createFeatureArray {
…
NSMutableArray *returnArray = [NSMutableArray array];
…
return returnArray;
}
Also, unless it is relevant to callers that the array is mutable, you should change that method to return NSArray instead of NSMutableArray. You could keep your code as is, i.e., return a mutable array even though the method declaration states that the return type is NSArray.
As for your convenience constructor, there are essentially two choices depending on whether you want to return an owned or a non-owned object:
if you want to return an owned object, allocate it with +alloc or +new and return it without autoreleasing it. Your method name should contain new, e.g. +newFeatureWithId:…
if you want to return an object that’s not owned by the caller, allocate it with +alloc or new and autorelease it before/upon returning it to the caller. Your method name should not contain new, alloc, or copy.
In -setUpNavigationButtons, you obtain a non-owned array via +createFeatureArray, allocate a mutable array based on it, and release the mutable array without adding or removing elements from it. A mutable array makes sense when you need to add/remove elements. If you don’t have this need, you could change your method to:
- (void)setUpNavigationButtons {
// get array of features from feature data controller object
NSArray *featureArray = [FeatureController createFeatureArray];
…
// [featureArray release];
You’d remove that [featureArray release] since you do not own featureArray inside that method.
Edit: In -setUpNavigationButtons, you’re retaining the button you create and soon after you’re releasing it. In that particular method, those are idempotent operations — they aren’t wrong per se but are not necessary at all. You could replace that code with
UIButton *aButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
…
[self.view addSubview:aButton];
// [aButton release];
i.e., do not retain it and do not release it.

UIView as dictionary key?

I want to have a NSDictionary that maps from UIViews to something else.
However, since UIViews do not implement the NSCopying protocol, I can't use them directly as dictionary keys.
You can use an NSValue holding the pointer to the UIView and use this as key. NSValues
are copyable. but, if the view is destroyed, the NSValue will hold a
junk pointer.
Here is the actual code (based on the answer by luvieere and further suggestion by Yar):
// create dictionary
NSMutableDictionary* dict = [NSMutableDictionary new];
// set value
UIView* view = [UILabel new];
dict[[NSValue valueWithNonretainedObject:view]] = #"foo";
// get value
NSString* foo = dict[[NSValue valueWithNonretainedObject:view]];
Although this isn't really what they're intended for, you could whip up a functional dictionary-like interface using Associative References:
static char associate_key;
void setValueForUIView(UIView * view, id val){
objc_setAssociatedObject(view, &associate_key, val, OBJC_ASSOCIATION_RETAIN);
}
id valueForUIView(UIView * view){
return objc_getAssociatedObject(view, &associate_key);
}
You could even wrap this up in a class ThingWhatActsLikeADictionaryButWithKeysThatArentCopyable*; in that case you might want to retain the views that you use as keys.
Something like this (untested):
#import "ThingWhatActsLikeADictionaryButWithKeysThatArentCopyable.h"
#import <objc/runtime.h>
static char associate_key;
#implementation ThingWhatActsLikeADictionaryButWithKeysThatArentCopyable
- (void)setObject: (id)obj forKey: (id)key
{
// Remove association and release key if obj is nil but something was
// previously set
if( !obj ){
if( [self objectForKey:key] ){
objc_setAssociatedObject(key, &associate_key, nil, OBJC_ASSOCIATION_RETAIN);
[key release];
}
return;
}
[key retain];
// retain/release for obj is handled by associated objects functions
objc_setAssociatedObject(key, &associate_key, obj, OBJC_ASSOCIATION_RETAIN);
}
- (id)objectForKey: (id)key
{
return objc_getAssociatedObject(key, &associate_key);
}
#end
*The name may need some work.
Provided you don't need to support before iOS 6, NSMapTable (suggested by neilsbot) works well because it can provide an enumerator over the keys in the collection. That's handy for code common to all of the text fields, like setting the delegate or bi-directionally syncing the text values with an NSUserDefaults instance.
in viewDidLoad
self.userDefFromTextField = [NSMapTable weakToStrongObjectsMapTable];
[self.userDefFromTextField setObject:#"fooUserDefKey" forKey:self.textFieldFoo];
[self.userDefFromTextField setObject:#"barUserDefKey" forKey:self.textFieldBar];
// skipped for clarity: more text fields
NSEnumerator *textFieldEnumerator = [self.userDefFromTextField keyEnumerator];
UITextField *textField;
while (textField = [textFieldEnumerator nextObject]) {
textField.delegate = self;
}
in viewWillAppear:
NSEnumerator *keyEnumerator = [self.userDefFromTextField keyEnumerator];
UITextField *textField;
while (textField = [keyEnumerator nextObject]) {
textField.text = [self.userDefaults stringForKey:[self.textFields objectForKey:textField]];
}
in textField:shouldChangeCharactersInRange:replacementString:
NSString *resultingText = [textField.text stringByReplacingCharactersInRange:range withString:string];
if(resultingText.length == 0) return YES;
NSString *preferenceKey = [self.textFields objectForKey:textField];
if(preferenceKey) [self.userDefaults setString:resultingText forKey:preferenceKey];
return YES;
And now I will go cry, because I implemented all of this before realizing that my iOS 5.1-targeted app can't use it. NSMapTable was introduced in iOS 6.
Rather than store a pointer to the view and risk the garbage issue, just give the UIView a tag and store the tag's value in the dictionary. Much safer.
I'm using a simple solution under ARC provided by Objective-C++.
MyClass.mm:
#import <map>
#implementation MyClass
{
std::map<UIView* __weak, UIColor* __strong> viewMap;
}
- (void) someMethod
{
viewMap[self.someView] = [UIColor redColor];
}
In this example I am getting stronger type checking by making all the values have to be a UIColor* which is all I needed this for. But you could also use id as the value type if you want to allow any object as the value, ex: std::map<UIView* __weak, id __strong> viewMap; Likewise for keys: id __weak, id __strong> viewMap;
You can also vary the __strong and __weak attributes as needed. In my case, the views are already retained by the view controller that I use this in, so I saw no need to take a strong pointer to them.
a simple solution when you just want UIView as key occasionally,I use it to store UILabel and UIColor
NSArray<UIView *> *views = #[viewA,viewB,viewC,viewD];
NSArray *values = #[valueA,valueB,valueC,valueD];
for(int i = 0;i < 4;i++) {
UIView *key = views[i];
id value = values[i]
//do something
}
id value = values[[views indexOfObject:key]]

Retrieve NSNumber From Array

I am relatively new to Objective C and need some array help.
I have a plist which contains a Dictionary and an NSNumber Array, with more arrays to
be added later on.
NSMutableDictionary *mainArray = [[NSMutableDictionary alloc]initWithContentsOfFile:filePath];
NSArray *scoresArray = [mainArray objectForKey:#"scores"];
I need to retrieve all the values from the array and connect them to 10 UILabels which
I've set up in interface builder. I've done the following to cast the NSNumber to a String.
NSNumber *numberOne = [scoresArray objectAtIndex:0];
NSUInteger intOne = [numberOne intValue];
NSString *stringOne = [NSString stringWithFormat:#"%d",intOne];
scoreLabel1.text = stringOne;
This seems a very long winded approach, I'd have to repeat the 4 lines above ten times to retrieve all the array values. Could I use a for loop to iterate through the array with all of the values converted to Strings at the output?
Any info would be greatly appreciated.
// create NSMutableArray* of score UILabel items, called "scoreLabels"
NSMutableArray *scoreLabels = [NSMutableArray arrayWithCapacity:10];
[scoreLabels addObject:scoreLabel1];
[scoreLabels addObject:scoreLabel2];
// ...
NSUInteger _index = 0;
for (NSNumber *_number in scoresArray) {
UILabel *_label = [scoreLabels objectAtIndex:_index];
_label.text = [NSString stringWithFormat:#"%d", [_number intValue]];
_index++;
}
EDIT
I'm not sure why you'd want to comment out _index++. I haven't tested this code, so maybe I'm missing something somewhere. But I don't see anything wrong with _index++ — that's a pretty standard way to increment a counter.
As an alternative to creating the scoreLabels array, you could indeed retrieve the tag property of the subviews of the view controller (in this case, UILabel instances that you add a tag value to in Interface Builder).
Assuming that the tag value is predictable — e.g., each UILabel from scoreLabel1 through scoreLabel10 is labeled with a tag equal to the values of _index that we use in the for loop (0 through 9) — then you could reference the UILabel directly:
// no need to create the NSMutableArray* scoreLabels here
NSUInteger _index = 0;
for (NSNumber *_number in scoresArray) {
UILabel *_label = (UILabel *)[self.view viewWithTag:_index];
_label.text = [NSString stringWithFormat:#"%d", [_number intValue]];
_index++;
}
The key to making that work is that the tag value has to be unique for the UILabel and must be something you can reference with -viewWithTag:.
The code above very simply assumes that the tag values are the same as the _index values, but that isn't required. (It also assumes the UILabel instances are subviews of the view controller's view property, which will depend on how you set up your interface in Interface Builder.)
Some people write functions that add 1000 or some other integer that allows you group types of subviews together — UILabel instances get 1000, 1001, and so on, and UIButton instances would get 2000, 2001, etc.
try using stringValue...
scoreLabel1.text = [(NSNumber *)[scoresArray objectAtIndex:0] stringValue];