I'm attempting to use resolveClassMethod: and object_addMethod to add a new method. Things seem to be working fine in general, but the parameter doesn't seem to be coming through.
When I pass in a parameter, such as:
UIFont *font1 = [UIFont academyEngravedLetPlainOfSize:12.0f];
I get 0.0 instead of 12.0 for the font size in my dynamic method. Here's the output from the sample below:
createNamedFontIMP(UIFont, academyEngravedLetPlainOfSize:, 0.000000)
What am I doing wrong here?
#interface UIFont (NTNamedFonts)
+(UIFont *)academyEngravedLetPlainOfSize:(int)size NS_AVAILABLE_IOS(6_0);
#end
#implementation UIFont (NTNamedFonts)
NSString *targetSelectorName = #"academyEngravedLetPlainOfSize:";
NSString *targetFontName = #"AcademyEngravedLetPlain";
+(BOOL)resolveClassMethod:(SEL)sel
{
NSString *selectorName = NSStringFromSelector(sel);
if ( [selectorName isEqualToString:targetSelectorName] )
{
Class metaClass = object_getClass(self);
class_addMethod(metaClass, sel, (IMP)createNamedFontIMP, "##:f");
return YES;
}
else
return [super resolveClassMethod:sel];
}
static id createNamedFontIMP(Class class, SEL _cmd, CGFloat size)
{
NSLog(#"createNamedFontIMP(%#, %#, %f)", NSStringFromClass(class), NSStringFromSelector(_cmd), size);
UIFont *font = [class fontWithName:targetFontName size:size];
return font;
}
#end
You pass an integer to a float. Please show the method declaration.
BTW: What's the reason for your code? A category seems to be the better approach.
BTW 2: If I remember correctly, you have to use double.
Related
I wanted to get only array string value app. As example(SLGoogleAuth ,HalfTunes,TheBackgrounder,Calculiator) . But don't know how to do?
It's a code.
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
//
Class LSApplicationWorkspace_class = objc_getClass("LSApplicationWorkspace");
SEL selector=NSSelectorFromString(#"defaultWorkspace");
NSObject* workspace = [LSApplicationWorkspace_class performSelector:selector];
SEL selectorALL = NSSelectorFromString(#"allApplications");
NSLog(#"apps: %#", [workspace performSelector:selectorALL]);
}
It's output:
Thanks in advance
You do not want to parse that. NSLog prints out a description of an object. You want to access that value directly.
[LSApplicationWorkspace allApplications];
returns NSArray of LSApplicationProxy. LSApplicationProxy class has a ivar _bundleURL that contains information that you need. You need runtime functions to access it. Working example below:
// #import <objc/runtime.h>
Class LSApplicationWorkspace_class = objc_getClass("LSApplicationWorkspace");
SEL selector=NSSelectorFromString(#"defaultWorkspace");
NSObject* workspace = [LSApplicationWorkspace_class performSelector:selector];
SEL selectorALL = NSSelectorFromString(#"allApplications");
NSArray* appProxies = [workspace performSelector:selectorALL];
Ivar bundleUrlIvar = class_getInstanceVariable([appProxies.firstObject class], "_bundleURL");
NSMutableString* result = [NSMutableString string];
for (id appProxy in appProxies)
{
NSURL* url = object_getIvar(appProxy, bundleUrlIvar);
// at this point you have the information and you can do whatever you want with it
// I will make it a list as you asked
if (url)
{
[result appendFormat:#",%#", [url lastPathComponent]];
}
}
if (result.length > 0)
{
// remove comma from beginning of the list
[result deleteCharactersInRange:NSMakeRange(0, 1)];
}
NSLog(#"apps: %#", result);
Note that this will be rejected by AppStore as you are using private apis. So use at your own discretion.
What would be "if let" equivalent in Objective C? The example snippet I want to convert to Objective C is below;
if let pfobjects = images as? [PFObject] {
if pfobjects.count > 0 {
var imageView: PFImageView = PFImageView()
imageView.file = pfobjects[0] as! PFFile
imageView.loadInBackground()
}
}
There's no direct equivalent to if let in Objective-C, because if let does Swift-specific things (unwrapping optionals and rebinding identifiers) that don't have direct equivalents in Objective-C.
Here's a nearly equivalent of your Swift code:
if (images != nil) {
NSArray<PFObject *> *pfobjects = (id)images;
if (pfobjects.count > 0) {
PFImageView *imageView = [[PFImageView alloc] init];
assert([pfobjects[0] isKindOfClass:[PFFile class]]);
imageView.file = (PFFile *)pfobjects[0];
[imageView loadInBackground];
}
}
But this Objective-C code won't verify that images only contains instances of PFObject, and should successfully create an image view as long as pfobjects[0] is a PFFile. Your Swift code will do nothing (create no image view) if images contains any non-PFObject elements.
You can use NSPredicate to verify the array contains only instances of PFObject:
NSPredicate *p = [NSPredicate predicateWithFormat:#"self isKindOfClass: %#", [PFObject class]];
NSInteger numberThatArePFObjects = [images filteredArrayUsingPredicate:p].count;
if(numberThatArePFObjects && numberThatArePFObjects == images.count){
// certain that images only contains instances of PFObject.
}
If however you weren't working with an array but a single object then it is simpler:
if([image isKindOfClass:[PFObject class]]){
// certain that image is a valid PFObject.
}
Or if you wanted a new variable:
PFObject* obj = nil;
if([image isKindOfClass:[PFObject class]] && (obj = image)){
// certain that obj is a valid PFObject.
}
You can use something like this:
NSArray<PFObject *> *pfobjects;
if ([images isKindOfClass: [NSArray<PFObject> class]] && (pfobjects = images)) {
// your code here
}
You want three things simultaneously. Let's split them:
variable as? OtherType is possible, but erases type, because it returns id. Implementation is as easy as a category on NSObject class, so it becomes NSArray *array = [jsonDict[#"objects"] ifKindOfClass:NSArray.class].
Implementation
#interface NSObject (OptionalDowncast)
- (id)ifKindOfClass:(__unsafe_unretained Class)clazz;
#end
#implementation NSObject (OptionalDowncast)
- (id)ifKindOfClass:(__unsafe_unretained Class)clazz {
return [self isKindOfClass:clazz] ? self : nil;
}
#end
if let is also possible in Objective-C if type is known, so it cannot be combined with previous thing. Easiest way is: for(NSArray *array = [self getItems]; array != nil; array = nil) { ... }, but if you want to use else branch, it gets a bit more complex. I have made SwiftyObjC pod for that, please take a look
Check generic template is not possible during type cast in Objective-C, thus you can cast to NSArray, but you can't cast to NSArray<PFObject>
I don't see iterations over your array: With all that being said, I think best example is (assuming images is an array already):
for(PFFile *file = [images.firstObject ifKindOfClass:PFFile.class]; file != nil; file = nil) {
imageView.file = file;
[imageView loadInBackground];
}
If you need to also iterate over it:
for(id object in images) {
for(PFFile *file = [object ifKindOfClass:PFFile.class]; file != nil; file = nil) {
//operate on file
}
}
You can use Objective-C++ in place of Objective-C. In this you can use the next define:
#define let const auto
Note: it is not the same exactly (Swift has wrapped values, ...) but it makes the work easier.
And through of this define you can use it of this way:
if (let pfobjects = images) {
if (pfobjects.count > 0 {
let imageView = [[PFImageView alloc] init];
imageView.file = pfobjects[0];
imageView loadInBackground();
}
}
To convert your Objective-C class in Objective-C++ class you only must change the extension of implementation file of .m to .mm
I'm fairly new to Objective-C; but have been coding for years and this one really stumps me.
I'm trying to build an iPhone app and wanted to create a "settings" screen which will use a Table format. (Xcode 5.1.1).
I want to future proof the main Settings screen and make it easy for the application coding by hiding the "hard work" in subroutines/methods.
I may be getting too clever but I've created a class for each 'setting' that contains screen prompts, default values etc and using an Enum to cross-reference it (so the compiler will highlight typos etc)
The problem I'm encountering is that when I add entries to my NSMutableDictionary and use lldb to print the values; every entry seems to have the same "key" and values. I've tried converting the eNum to an NSNumber and also as an NSString -- no difference in the result - so I'm obviously doing something else daft but just can't see it
The following code is from various .m & .h files, I've omitted boring stuff that you always "have to have" to keep it short
// basic x-ref I want to use in my code
typedef NS_OPTIONS(NSInteger, ConfigurationType) {
unDefined = -1,
Server = 0,
Id = 1,
Phone = 2
};
// definition for a "single" Settings value
#interface SettingDefinition : NSObject
#end
#implementation SettingDefinition
ConfigurationType _cfgType;
NSString *_cfgName;
NSString *_screenTitle;
NSString *_value;
- (NSString *)description
{
NSString *className = NSStringFromClass([self class]);
return [NSString stringWithFormat:#"<%#: x%p Type=%d dbKey=%# '%#' -> %#>", className, self, _cfgType, _cfgName, _screenTitle, _value];
}
- (id)initType:(ConfigurationType)cfgOption
withDbKey: (NSString*)dbKey
asOptionTitle:(NSString*)cfgTitle
withValue:(NSString*)itmValue
{
self = [super init];
if (self) {
_screenTitle = cfgTitle;
_cfgName = dbKey;
_cfgType = cfgOption;
_value = itmValue;
}
return self;
}
#end
#interface Configuration : NSObject
#end
#implementation Configuration {
NSMutableDictionary *Settings; // List of Setting structures
};
- (id)init {
self = [super init];
if (self) {
Settings = [[NSMutableDictionary alloc]init];
[self add:Server withDbKey:#"Server" asOptionTitle:#"Server"];
[self add:Id withDbKey:#"Id" asOptionTitle:#"Your ID"];
[self add:Phone withDbKey:#"Phone" asOptionTitle:#"Phone No."];
}
return self;
}
- (void) add:(ConfigurationType)cfgOption
withDbKey:(NSString*)dbKey
asOptionTitle:(NSString*)cfgTitle
{
NSString * itmValue = [self configurationValue: cfgOption cfgName:dbKey];
SettingDefinition *x = [[SettingDefinition alloc]
initType: cfgOption
withDbKey: dbKey
asOptionTitle: cfgTitle
withValue: itmValue];
[Settings setObject:x forKey:[self asKey:cfgOption]];
}
- (NSString *) asKey:(ConfigurationType) settingType {
NSString *rc = [NSString stringWithFormat:#"%d", settingType];
return rc;
}
- (NSString *) configurationValue:(ConfigurationType) settingType {
// returns a suitable value from my system setup
// which is initially a null value until the user sets everything up
}
the debug window shows the following when I break after the final call to [self add: ...]
(lldb) po Settings
{
0 = "<SettingDefinition: x0x8e7c280 Type=2 dbKey=Phone 'Phone No.' -> (null)>";
1 = "<SettingDefinition: x0x8c703a0 Type=2 dbKey=Phone 'Phone No.' -> (null)>";
2 = "<SettingDefinition: x0x8e7c310 Type=2 dbKey=Phone 'Phone No.' -> (null)>";
}
The (null) is obviously due to no data in 'value' yet; but why do they all show as 'Phone'; if I break after the second call to [self add:..] they all show as 'Id'
UPDATE:
DOH! obviously they're globals (I've been using another IDE where everything is local until exposed) .. If I enclose them in braces in the implementation as the documentation states then the exhibited problem vanishes. I have properties to access the variables but as the setter does more than just set the memory, I thought I'd need my "own" variables to hold the data.. said it was something daft .. thank you!
Hey I have a bit of code that keeps returning an error message, but i can't figure out what the problem is. I am fairly new to Objective-c syntax so it could be something fairly simple, however i can not seem to find the problem. The method is
-(void)setPlayerPosition:(CGPoint) position {
CGPoint tileCoord = [self tileCoordForPosition:position];
int tileGid = [metaLayer tileGIDAt:tileCoord];
if (tileGid) {
NSDictionary *properties = [tileMap propertiesForGID:tileGid];
if (properties) {
NSString *collision = [properties valueForKey:#"Collidable"];
if (collision && [collision compare:#"True"] == NSOrderedSame) {
return;
}
NSString *collectable = [properties valueForKey:#"Collectable"];
if (collectable && [collectable compare:#"True"] == NSOrderedSame) {
[metaLayer removeTileAt:tileCoord];
[foreground removeTileAt:tileCoord];
}
}
}
player.position = position;
}
It returns the error Invalid initializer for the 2nd line and also says that my class may not respond to 'tileCoordForPosition:' Any help would be appreciated!
I assume you are following the article at http://www.raywenderlich.com/1186/collisions-and-collectables-how-to-make-a-tile-based-game-with-cocos2d-part-2
So after briefly reading it myself, my guess is you are either missing the method required or are not declaring it properly in your class.
You should have the following method declared and implemented
- (CGPoint)tileCoordForPosition:(CGPoint)position
And it should be in the same class as where you call it on self
[self tileCoordForPosition:position]
If you do have that method implemented in your class then make sure you are declaring it correctly too. Try adding it to the top of your .m file like so
#interface YourControllerNameHere()
- (CGPoint)tileCoordForPosition:(CGPoint)position;
#end
You need to declare tileCoordForPosition: in your header so the compiler knows what type it returns (in this case, a CGPoint).
I need a way to pass a property and get the name assigned to it. Any suggestions?
#property (nonatomic, retain) MyObject *crazyObject;
NSString *str = SOME_WAY_TO_GET_PROPERTY_NAME(crazyObject);
// Above method should return #"crazyObject"
You can try this:
unsigned int propertyCount = 0;
objc_property_t * properties = class_copyPropertyList([self class], &propertyCount);
NSMutableArray * propertyNames = [NSMutableArray array];
for (unsigned int i = 0; i < propertyCount; ++i) {
objc_property_t property = properties[i];
const char * name = property_getName(property);
[propertyNames addObject:[NSString stringWithUTF8String:name]];
}
free(properties);
NSLog(#"Names: %#", propertyNames);
It's as simple as this...expanding upon what Chuck already mentioned:
#ifndef STR_PROP
#define STR_PROP( prop ) NSStringFromSelector(#selector(prop))
#endif
You then use it like so:
NSString *strProp = STR_PROP(myProperty);
Background
Keep in mind that properties are really just, to quote Apple, "a syntactical shorthand for declaring a class’s accessor methods." In fact, by itself, the #property declaration doesn't even work. Your #synthesize statement translates the #property into the equivalent of two methods:
- (void)setCrazyObject:(MyObject *)something;
- (MyObject *)crazyObject;
Which one is used depends on the context surrounding your self.crazyObject. (#synthesize also creates a matching instance variable if you didn't do it yourself.) The offshoot of all this is that you can't really translate to and from a property with one single method.
Proposed Solution
You can use what Apple already provides:
NSString *foo = NSStringFromSelector(#selector(myClassProperty));
Or do something custom:
Given that self.crazyObject really translates to either [self crazyObject] or [self setCrazyObject:foo] by the time your code is running, ou'll probably need two methods, like:
- (NSString *)setterStringForProperty:(SEL)prop;
- (NSString *)getterStringForProperty:(SEL)prop;
You might then want at least 2 companion methods such as:
- (SEL)setterForPropertyName:(NSString *)propString;
- (SEL)getterForPropertyName:(NSString *)propString;
Within these methods, you can use the Foundation functions NSStringFromSelector and NSSelectorFromString to convert back and forth between SEL and NSString. Use whatever string manipulations you like to convert back and forth between your setter string (setCrazyObject) and your property name (crazyObject).
A complete solution is hard to provide without knowing the exact use case, but hopefully this provides some more clues for anyone trying to accomplish something similar. There might even be some useful things made possible by combining this approach with Oscar's answer.
Here is a function that returns the name of an ivar, so basically it not only returns the properties but any ivar of the class. I haven't found a way to get the property directly so I used the ivar trick.
#import <objc/objc.h>
/// -----
- (NSString *)nameOfIvar:(id)ivarPtr
{
NSString *name = nil;
uint32_t ivarCount;
Ivar *ivars = class_copyIvarList([self class], &ivarCount);
if(ivars)
{
for(uint32_t i=0; i<ivarCount; i++)
{
Ivar ivar = ivars[i];
id pointer = object_getIvar(self, ivar);
if(pointer == ivarPtr)
{
name = [NSString stringWithUTF8String:ivar_getName(ivar)];
break;
}
}
free(ivars);
}
return name;
}
After searching and debugging i find solution for me...
Added #import <objc/runtime.h>
Methods object_getIvar(id obj, Ivar ivar) send bad access and app crashes. i modify some code and it worked great:
+(NSString*)stringWithProperty:(id)property withClass:(id)controller
{
NSString *name = nil;
uint32_t ivarCount;
Ivar *ivars = class_copyIvarList([controller class], &ivarCount);
if(ivars)
{
for(uint32_t i=0; i<ivarCount; i++)
{
Ivar ivar = ivars[i];
name = [NSString stringWithUTF8String:ivar_getName(ivar)];
if ([controller valueForKey:name] == property)
{
break;
}
}
free(ivars);
}
return name;
}
Modifying the solution, it works when your object is allocated already, otherwise it returns nil:-
NSString * NSStringFromProperty(NSObject* property, NSObject* class)
{
unsigned int propertyCount = 0;
objc_property_t * properties = class_copyPropertyList([class class], &propertyCount);
NSString *name = nil;
for (unsigned int i = 0; i < propertyCount; ++i)
{
name = [NSString stringWithUTF8String:property_getName(properties[i])];
NSObject *object = [class valueForKey:name];
if (object != nil && object == property)
{
break;
}
else
{
name = nil;
}
}
free(properties);
return name;
}
You can use
NSString *str = NSStringFromSelector(#selector(crazyObject));
The good thing about this approach is that:
Xcode will autocomplete word crazyObject for you.
When later on you will change the property name from crazyObject to myCrazyObject, Xcode will add a warning saying "unrecognized selector!" -- pretty good for debugging.
I use this method so often, that I even created a function, which allows to write less letters:
NSString * __nonnull sfs(SEL __nonnull theSelector)
{
if (!theSelector)
{
abort();
}
return NSStringFromSelector(theSelector);
}
Now your final solution can look like this:
NSString *str = sfs(#selector(crazyObject));
From Get property name as string, without using the runtime reference library, just define:
#define propertyKeyPath(property) (#""#property)
#define propertyKeyPathLastComponent(property) [[(#""#property) componentsSeparatedByString:#"."] lastObject]
And then you can do something like this:
NSLog(#"%#", propertyKeyPathLastComponent(appleStore.storeLocation.street)); //result: street
You may check my approach at Gist to get the string for a property with autocompletion and compile-time check.
How to use:
Get the property name for a class:
#interface AnyClass : NSObject
#property (strong) NSData *data;
#end
// == My approach ==
// C string for a class
PropertyNameForClass(AnyClass, data); // ==> "data"
// NSString for a class
PropertyStringForClass(AnyClass, data); // ==> #"data"
// Bad approach (no autocompletion; no compile-time check):
NSString *propertyName = #"data";
Get the property name for a protocol:
#protocol AnyProtocol
#property (strong) NSDate *date;
#end
// C string for a protocol
PropertyNameForProtocol(AnyProtocol, date); // ==> "date"
// NSString for a protocol
PropertyStringForProtocol(AnyProtocol, date); // ==> #"date"
Unconventional, hacky, ugly, late, but... as strong-named as it gets and works like a charm:
#define SOME_WAY_TO_GET_PROPERTY_NAME(p) p == p ? [[[[[[[NSString alloc] initWithCString:#p encoding:NSUTF8StringEncoding] componentsSeparatedByString:#"."] lastObject] componentsSeparatedByString:#" "] lastObject] stringByReplacingOccurrencesOfString:#"]" withString:#""] : #""
Sample usage:
NSLog(SOME_WAY_TO_GET_PROPERTY_NAME(self.customer.surname)); // surname
NSLog(SOME_WAY_TO_GET_PROPERTY_NAME([[self customer] birthDate])); // birthDate
...