I've got an observer on my textFields which looks to see if the "enabled# property has changed.
(void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *) context;
{
UITextField *txtField = (UITextField *)object;
BOOL new = [[change objectForKey:NSKeyValueChangeNewKey] boolValue];
BOOL old = [[change objectForKey:NSKeyValueChangeOldKey] boolValue];
if ((new != old) && (new = YES))
{
[self fadeDisable:txtField];
}
else if ((new != old) && (new = NO))
{
[self fadeEnable:txtField];
}
I thought if I used int new and int old, the 1 or 0 which defined if the property is enabled or not would be returned but when I use NSLog to see what thy are bringing back, it's a long string of numbers.
I looked through the documentation and it seems that objectForKey actually return an id not an integer but i'm not sure what to do.
Edit: i've added the code for my comparison which is trying to determine if it went from disabled to enabled (or vice versa). Also added the boolValue correction as recommended.
It does not give the intended result and doesn't call the correct method. Is it correct?
Thanks
NSDictionary contains objects (like NSNumber), not primitive types (like int). As you have noticed,
[change objectForKey:NSKeyValueChangeNewKey]
returns id. If you want to convert it to int, use
int new = [[change objectForKey:NSKeyValueChangeNewKey] intValue]
Or if the property is a BOOL, even better:
BOOL new = [[change objectForKey:NSKeyValueChangeNewKey] boolValue]
This line of code
int new = [change objectForKey:NSKeyValueChangeNewKey]
results in storing value of pointer to the NSNumber object into new integer, this is the "long string of numbers" you mentioned. Strangely, it does compile without even a warning.
Is there a more intelligent way to rewrite this?
if ([cardName isEqualToString:#"Six"]) {
[self setValue:6];
} else if ([cardName isEqualToString:#"Seven"]) {
[self setValue:7];
} else if ([cardName isEqualToString:#"Eight"]) {
[self setValue:8];
} else if ([cardName isEqualToString:#"Nine"]) {
[self setValue:9];
}
Unfortunately they cannot. This is one of the best and most sought after utilizations of switch statements, so hopefully they hop on the (now) Java (and others) bandwagon!
If you are doing card names, perhaps assign each card object an integer value and switch on that. Or perhaps an enum, which is considered as a number and can therefore be switched upon.
e.g.
typedef enum{
Ace, Two, Three, Four, Five ... Jack, Queen, King
} CardType;
Done this way, Ace would be be equal to case 0, Two as case 1, etc.
You could set up a dictionary of blocks, like this:
NSString *lookup = #"Hearts"; // The value you want to switch on
typedef void (^CaseBlock)();
// Squint and this looks like a proper switch!
NSDictionary *d = #{
#"Diamonds":
^{
NSLog(#"Riches!");
},
#"Hearts":
^{
self.hearts++;
NSLog(#"Hearts!");
},
#"Clubs":
^{
NSLog(#"Late night coding > late night dancing");
},
#"Spades":
^{
NSLog(#"I'm digging it");
}
};
((CaseBlock)d[lookup])(); // invoke the correct block of code
To have a 'default' section, replace the last line with:
CaseBlock c = d[lookup];
if (c) c(); else { NSLog(#"Joker"); }
Hopefully Apple will teach 'switch' a few new tricks.
For me, a nice easy way:
NSString *theString = #"item3"; // The one we want to switch on
NSArray *items = #[#"item1", #"item2", #"item3"];
int item = [items indexOfObject:theString];
switch (item) {
case 0:
// Item 1
break;
case 1:
// Item 2
break;
case 2:
// Item 3
break;
default:
break;
}
Unfortunately, switch statements can only be used on primitive types. You do have a few options using collections, though.
Probably the best option would be to store each value as an entry in an NSDictionary.
NSDictionary *stringToNumber = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:6],#"Six",
[NSNumber numberWithInt:7],#"Seven",
[NSNumber numberWithInt:8],#"Eight",
[NSNumber numberWithInt:9],#"Nine",
nil];
NSNumber *number = [stringToNumber objectForKey:cardName];
if(number) [self setValue:[number intValue]];
A bit late but for anyone in the future I was able to get this to work for me
#define CASE(str) if ([__s__ isEqualToString:(str)])
#define SWITCH(s) for (NSString *__s__ = (s); ; )
#define DEFAULT
Here is the more intelligent way to write that. It's to use an NSNumberFormatter in the "spell-out style":
NSString *cardName = ...;
NSNumberFormatter *nf = [[NSNumberFormatter alloc] init];
[nf setNumberStyle:NSNumberFormatterSpellOutStyle];
NSNumber *n = [nf numberFromString:[cardName lowercaseString]];
[self setValue:[n intValue]];
[nf release];
Note that the number formatter wants the string to be lowercased, so we have to do that ourselves before passing it in to the formatter.
There are other ways to do that, but switch isn't one of them.
If you only have a few strings, as in your example, the code you have is fine. If you have many cases, you could store the strings as keys in a dictionary and look up the corresponding value:
NSDictionary *cases = #{#"Six" : #6,
#"Seven" : #7,
//...
};
NSNumber *value = [cases objectForKey:cardName];
if (value != nil) {
[self setValue:[value intValue]];
}
BY FAR.. my FAVORITE "ObjC Add-On" is ObjectMatcher
objswitch(someObject)
objcase(#"one") { // Nesting works.
objswitch(#"b")
objcase(#"a") printf("one/a");
objcase(#"b") printf("one/b");
endswitch // Any code can go here, including break/continue/return.
}
objcase(#"two") printf("It's TWO."); // Can omit braces.
objcase(#"three", // Can have multiple values in one case.
nil, // nil can be a "case" value.
[self self], // "Case" values don't have to be constants.
#"tres", #"trois") { printf("It's a THREE."); }
defaultcase printf("None of the above."); // Optional default must be at end.
endswitch
AND it works with non-strings, TOO... in loops, even!
for (id ifNumericWhatIsIt in #[#99, #0, #"shnitzel"])
objswitch(ifNumericWhatIsIt)
objkind(NSNumber) printf("It's a NUMBER.... ");
objswitch([ifNumericWhatIsIt stringValue])
objcase(#"3") printf("It's THREE.\n");
objcase(#"99") printf("It's NINETY-NINE.\n");
defaultcase printf("some other Number.\n");
endswitch
defaultcase printf("It's something else entirely.\n");
endswitch
It's a NUMBER.... It's NINETY-NINE.
It's a NUMBER.... some other Number.
It's something else entirely.
Best of all, there are SO few {...}'s, :'s, and ()'s
Objective-c is no different from c in this aspect, it can only switch on what c can (and the preproc def's like NSInteger, NSUInteger, since they ultimately are just typedef'd to an integral type).
Wikipedia:
c syntax:
The switch statement causes control to be transferred to one of several statements depending on the value of an expression, which must have integral type.
Integral Types:
In computer science, an integer is a datum of integral data type, a
data type which represents some finite subset of the mathematical
integers. Integral data types may be of different sizes and may or may
not be allowed to contain negative values.
I'm kind of late to the party, but to answer the question as stated, there's a more intelligent way:
NSInteger index = [#[#"Six", #"Seven", #"Eight", #"Nine"] indexOfObject:cardName];
if (index != NSNotFound) [self setValue: index + 6];
Note that indexOfObject will look for the match using isEqual:, exactly as in the question.
Building on #Graham Perks idea posted earlier, designed a simple class to make switching on strings fairly simple and clean.
#interface Switcher : NSObject
+ (void)switchOnString:(NSString *)tString
using:(NSDictionary<NSString *, CaseBlock> *)tCases
withDefault:(CaseBlock)tDefaultBlock;
#end
#implementation Switcher
+ (void)switchOnString:(NSString *)tString
using:(NSDictionary<NSString *, CaseBlock> *)tCases
withDefault:(CaseBlock)tDefaultBlock
{
CaseBlock blockToExecute = tCases[tString];
if (blockToExecute) {
blockToExecute();
} else {
tDefaultBlock();
}
}
#end
You would use it like this:
[Switcher switchOnString:someString
using:#{
#"Spades":
^{
NSLog(#"Spades block");
},
#"Hearts":
^{
NSLog(#"Hearts block");
},
#"Clubs":
^{
NSLog(#"Clubs block");
},
#"Diamonds":
^{
NSLog(#"Diamonds block");
}
} withDefault:
^{
NSLog(#"Default block");
}
];
The correct block will execute according to the string.
Gist for this solution
You can use macros approach to achieve it:
#define CASE(str) if ([__s__ isEqualToString:(str)])
#define SWITCH(s) for (NSString *__s__ = (s); ; )
#define DEFAULT
SWITCH (string) {
CASE (#"TestString") {
break;
}
CASE (#"YetAnotherString") {
break;
}
CASE (#"Test") {
break;
}
DEFAULT {
break;
}
}
I can't Comment on cris's answer on #Cris answer but i would like to say that:
There is an LIMITATION for #cris's method:
typedef enum will not take alphanumeric values
typedef enum
{
12Ace, 23Two, 23Three, 23Four, F22ive ... Jack, Queen, King
} CardType;
So here is another One:
Link Stack over flow Go to this user answer "user1717750"
typedef enum
{
Six,
Seven,
Eight
} cardName;
- (void) switchcardName:(NSString *) param {
switch([[cases objectForKey:param] intValue]) {
case Six:
NSLog(#"Six");
break;
case Seven:
NSLog(#"Seven");
break;
case Eight:
NSLog(#"Eight");
break;
default:
NSLog(#"Default");
break;
}
}
Enjoy Coding.....
My application contains an NSTabView with two tabs. Further, the application itself has a playState which is an enum. The playState is kept in a Singleton.
typedef enum {
kMyAppPlayStatePlaying,
kMyAppPlayStatePaused
} MyAppPlayState;
The playState gets synthesized here.
#property (readwrite) MyAppPlayState playState;
I want to switch the NSTabView every time the playState changes. Therefore, I prepared an IBOutlet to add a binding similar to this one.
[self.playPauseTabView bind:#"selectedItemIdentifier" toObject:[MyAppState sharedState] withKeyPath:#"playState" options:nil];
I already recognized the identifier must be NSString. This does not match with my enum which is an int. I could maybe use an NSValueTransformer to fix this.
Further, selectedItemIdentifier does not exists. NSTabView only offers selectedTabViewItem which then allows to access identifier or label. Though, I cannot find a way to switch the item itself based on the identifer.
In situations like that, I find myself doing one of two things:
1) Register self (or some other object) as an observer of the property in question, and set the selected tab accordingly in -observeValueForKeyPath:ofObject:change:context:. It could look like this:
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
if ( context == PlayStateChange )
{
if ( [[change objectForKey: NSKeyValueChangeKindKey] integerValue] == NSKeyValueChangeSetting )
{
NSNumber *oldValue = [change objectForKey: NSKeyValueChangeOldKey];
NSNumber *newValue = [change objectForKey: NSKeyValueChangeNewKey];
NSInteger oldInteger = [oldValue integerValue];
NSInteger newInteger = [newValue integerValue];
NSLog(#"Old play state: %ld, new play state: %ld", (long)oldInteger, (long)newInteger);
// Do something useful with the integers here
}
return;
}
}
2) declare a readonly NSString * property and declare that its value is affected by your playState property. Something like this:
#property (readonly) NSString *playStateStr;
// Accessor
-(NSString *)playStateStr
{
return playState == kMyAppPlayStatePlaying ? #"playing" : "paused";
}
+(NSSet *)keyPathsForValuesAffectingPlayStateStr
{
return [NSSet setWithObject: #"playState"];
}
Now you have an NSString-typed property that you can bind your tab view's selection.
I forgot to connect the NSTabView with its IBOutlet in the Interface Builder.
The following works for me.
NSDictionary* playStateOptions = [NSDictionary dictionaryWithObject:[[PlayStateValueTransformer alloc] init] forKey:NSValueTransformerBindingOption];
[self.playPauseTabView bind:#"selectedLabel" toObject:[MyAppState sharedState] withKeyPath:#"playState" options:playStateOptions];
In the NSValueTransformer I return an NSString which must be set in Interface Builder for each tab!
i have this code and on the second line it gives me an error that says invalid initialzer
this is the code:
-(void)setPlayerPosition:(CGPoint)position {
CGPoint tileCoord = [self tileCoordForPosition:position];
int tileGid = [_meta tileGIDAt:tileCoord];
if (tileGid) {
NSDictionary *properties = [_tileMap propertiesForGID:tileGid];
if (properties) {
NSString *collision = [properties valueForKey:#"Collidable"];
if (collision && [collision compare:#"True"] == NSOrderedSame) {
return;
}
}
}
_player.position = position;
}
I have the same problem with you. But when I declare function [tileCoordForPosition] in .h file, everything is built success.
I'm going to use my psychic powers and guess that you accidentally declared tileCoordForPosition: as returning a CGPoint* (that is, a pointer to a CGPoint) rather than a CGPoint.
(It would, however, have been helpful if you'd shown the relevant code so I wouldn't have to fire up the ESP.)
I'm getting used to OCMock. Coming from a Java/JMock background I'm now looking for the ability to say [[[myMock stub] returnValueFromCustomMethod] someMockedMethod]; where returnValueFromCustomMethod is defined in the test class. I was originally thinking something along the terms of [[[myMock stub] usingSelector:#selector(myMethod:)] someMockedMethod]; but after writing I wonder if my first approach makes more sense. Either way, could someone show me if and how this can be done?
My original answer was off-track: OCMock doesn't support this! If you wanted to change OCMock to support this, you would need to do something like adding a BOOL returnValueIsFromInvocation field to OCMockRecorder, and add a method to set this up:
- (id)andReturnResultOfInvocation:(NSInvocation *)anInvocation {
returnValueIsFromInvocation = YES;
returnValueIsBoxed = NO;
returnValueShouldBeThrown = NO;
[returnValue autorelease];
returnValue = [anInvocation retain];
return self;
}
Then teach setUpReturnValue to call the invocation (changes are in bold):
- (void)setUpReturnValue:(NSInvocation *)anInvocation
{
if (returnValueIsFromInvocation) {
NSInvocation *returnValueInvocation = (NSInvocation *)returnValue;
[returnValueInvocation invoke];
void *buffer = malloc([[anInvocation methodSignature] methodReturnLength]);
[returnValueInvocation getValue:buffer];
[anInvocation setReturnValue:buffer];
free(buffer);
}
else if(returnValueShouldBeThrown)
{
#throw returnValue;
}
else if(returnValueIsBoxed)
{
if(strcmp([[anInvocation methodSignature] methodReturnType],
[(NSValue *)returnValue objCType]) != 0)
[NSException raise:NSInvalidArgumentException
format:#"Return value does not match method signature."];
void *buffer = malloc([[anInvocation methodSignature] methodReturnLength]);
[returnValue getValue:buffer];
[anInvocation setReturnValue:buffer];
free(buffer);
}
else
{
const char *returnType = [[anInvocation methodSignature] methodReturnType];
const char *returnTypeWithoutQualifiers = returnType + (strlen(returnType) - 1);
if(strcmp(returnTypeWithoutQualifiers, #encode(id)) == 0)
[anInvocation setReturnValue:&returnValue];
}
}
This change is difficult to do by introducing subclasses because you have to override the methods that return OCMockRecorders (like stub, expect and so on) but the concrete subclasses of OCMockObject (OCClassMockObject and OCProtocolMockObject) are hidden by the framework.