I've some really simple code that checks if my bool is == YES but it does not ever enter.
NSLog(#"boool %d",self.arrayAlreadyPopulated );
if (self.arrayAlreadyPopulated == YES)
{
Match *aMatch = [appDelegate.matchScoresArray objectAtIndex:(numMatchCounter)];
aMatch.teamName1 = TeamNameHolder;
}
else
{
Match *aMatch = [[Match alloc] init];
aMatch.teamName1 = TeamNameHolder;
[appDelegate.matchScoresArray addObject:aMatch];
[aMatch release];
}
The debug at the top says that the value of self.arrayAlreadyPopulated is 1 on the 2nd pass as it should be.
But it never enters the first first part but jumps down to the 'else'
I cant see for the life of me what the problem is. -.-
Anybody able to clue me in?
Thanks
-Code
EDIT declaration code
BOOL arrayAlreadyPopulated;
#property (nonatomic) BOOL arrayAlreadyPopulated;
#synthesize arrayAlreadyPopulated;
Don't compare a BOOL against YES or NO. They can carry values that are not NO but don't compare equal to YES. Instead, use the boolean expression directly in the if statement:
if (self.arrayAlreadyPopulated)
{
// ...
}
arrayAlreadyPopulated is probably not actually a BOOL. If, for example, it was a float, the %d would still print 1.
Check and double check that you're assigning the value to arrayAlreadyPopulated always as self.arrayAlreadyPopulated = YES instead of just arrayAlreadyPopulated = YES.
Sometimes, using the property v/s the associated variable of the property interchangeably doesn't always work out the way you'd expect it to. Use the "variable" name only if you're using it to release memory by [variable release] statement, just the way you'll find it in any Apple example code. In all other cases use self.propertyname.
Related
please look at this code:
-(NSString *) myfun:(NSString *)name paramnoone:(int)a paramnotwo:(int)b {
static int numberofcall=0;
if(a>b) {
return name;
}
NSString *secondname = [[NSString alloc]init];
secondname = [name StringByAppendingString:#"test"];
numberofcall++;
return secondname;
}
i have a problem on it, when my code is on "return secondname" next step is going to "return name" on if statement part, im confusing a lot , because c++ does not have this problem,
please help me on solve it,
thanks for ur help and sorry for my bad English.
(Until the question is explained further I can't really answer the question, but still have valuable infos which justify being posted as an answer, so here it goes.)
In the line:
NSString *secondname = [[NSString alloc]init];
You allocate an empty string. But in the very next line:
secondname = [name StringByAppendingString:#"test"];
You overwrite the pointer secondname to the previously allocated empty string, thus creating a memory leak. Since you do not use the empty string at all, remove the first line and turn the second line into:
NSString *secondname = [name StringByAppendingString:#"test"];
Edit: Based on comments to the questions, I think what you're asking is this (correct me if I'm wrong):
You are debugging the method.
While stepping through the method with the debugger, the flow proceeds normally through the method.
But after the numberofcall++; line, the debugger suddenly jumps to the return name; instead of the return secondname; line.
If that's what's happening to you: this is normal behavior, unfortunately. When the debugger reaches a return statement the marker always "jumps" to the first return statement in the method. But even though it doesn't look that way, your return secondname; statement is really executed.
When i typed [lat1 = newLocation.coordinate.latitude]; its telling expected : before ] token like that. whats my fault? as i am new to this domain., please ayone guide me.
Thanks In Prior....
If you are trying to compare lat1 and newLocation.coordinate.latitude, the correct statement would be:
if (lat1 == newLocation.coordinate.latitude) {
// do something here
}
If you are trying to assign the value of newLocation.coordinate.latitude into lat1, the correct statement is:
lat1 = newLocation.coordinate.latitude;
If you are trying to do the first thing and the compared variables are floating point numbers, then you probably want to check if they are close enough instead of equality:
if (fabs(lat1 - newLocation.coordinate.latitude) < someLittleDistance) {
// close enough
}
…where of course you will have to define someLittleDistance.
Try the following..
Remove the [] brackets from your line it must be
lat1 = newLocation.coordinate.latitude;
When xCode behaves like this, it probably wants to say that something is the method or it thinks of something like a method. Dot-notation in Objective-C as usual is some kind of equivalent of the setter. For example
ObjectA.property1 = value;
is equivalent of
[ObjectA setProperty1:value];
And in the last case, xCode expects to see : after the setter call and a value after the column.
I am confused about strings (a beginner's problem, I'm afraid):
I have one NSMutableArray called Notebook. At index position 1, I have an object, which I think is a string. At least I put it into the array like this:
[NoteBook replaceObjectAtIndex:1 withObject:#"x-x-x-x"];
So far so good. If I put this into an UILabel, it will show x-x-x-x on my screen. The nightmare starts when I try to compare this string with other strings. Let's consider that I do not want to display the string x-x-x-x on my screen, but just to have a blank instead. So I thought I could achieve this by coding this:
NSString *tempDateString;
tempDateString = [NSString stringWithFormat:#"%#",[NoteBook objectAtIndex:1]];
if (tempDateString == #"x-x-x-x") {
UISampleLabel.text = #"";
}
For some reason, this does not work, i.e. even if the string at position 1 of my array is 'x-x-x-x', it will still not set my UISampleLabel to nothing.
I suppose that I am getting confused with the #"" markers. When do I really need them? Why can't I simply code tempDateString = [NoteBook objectAtIndex:1]; without the formatting thing?
Any help and suggestions would be very much appreciated!
You need to compare string with isEqualToString:
if ([tempDateString isEqualToString:#"x-x-x-x"]) {
UISampleLabel.text = #"";
}
In addition to the question that's been answered:
Why can't I simply code tempDateString = [NoteBook objectAtIndex:1]; without the formatting thing?
You can. Why do you think you can't?
i'm new to iphone programming and i encountered/noticed some problems while i was coding. which was after i typed a statement like
if (label.text > label2.text) {
do something...}
however, after typing my application can be compiled and run however when i try to validate it by comparing the values, my specified actions can run and i can change my image view image, however the conditions is not true but the specified actions can be run. Do enlighten me thanks! i will post my codes at the bottom, do comment if you spot any better practices? thanks once again.
Oh and how can i specify to check in my label that the default value is not "Label" or empty because i would like the values to be populated with number before commencing.
-(IBAction) beginMatch {
if (resultP1.text, resultP2.text = #"Label") {
errorMsg.text = #"Please Press Roll (:";
}
else
if (resultP1.text > resultP2.text) {
MG = [MainGameController alloc];
MG.player1 = playerName.text;
}
else {
MG.player1 = playerNameP2.text;
}
[self.view addSubview:MG.view];
}
this is one example that it does not work i have another one which is below.
-(IBAction) btn:(id) sender {
ptc = [playerTurnController alloc];
if (ptc.player1name = MGplayerName.text) {
if (lblDiceResultP1.text > lblDiceResultP2.text) {
img.image = [UIImage imageNamed:#"yellow.png"];
}
else if (ptc.player2name = MGplayerName.text) {
img.image = [UIImage imageNamed:#"Blue.png"];
}
}
}
Thank you.
Your code contains quite a few errors. You're trying to compare NSString values with ">", you're using the comma operator and = operator incorrectly, and you're allocating new objects in (what look to be) the wrong places.
You really should work your way through the introductory documentation on Apple's developer website first:
Learning Objective-C: A Primer
and
Your First iPhone Application
In here you're comparing string (alphabetically) addresses:
lblDiceResultP1.text > lblDiceResultP2.text
You probably want to extract NSNumbers of out the strings and compare the numeric values.
This here is an assignment and not a comparison:
ptc.player2name = MGplayerName.text
You probably meant to use == which is also wrong.
NSStrings are compared with the isEqualToString e.g.
NSString * s1 = #"String One";
NSString * s2 = #"String Two";
if([s1 isEqualToString:s2])
// do something when strings are equal
I am having a strange problem with boolean logic. I must be doing something daft, but I can't figure it out.
In the below code firstMeasure.isInvisibleArea is true and measureBuffer1 is nil.
Even though test1 is evaluating to NO for some reason it is still dropping into my if statement.
It works ok if I use the commented out line.
Any idea why this happens?
BOOL firstVisible = firstMeasure.isInVisibleArea;
BOOL notFirstVisible = !(firstMeasure.isInVisibleArea);
BOOL measureBufferNil = measureBuffer1 == nil;
BOOL test1 = measureBuffer1 == nil && !firstMeasure.isInVisibleArea;
BOOL test2 = measureBufferNil && !firstVisible;
if (measureBuffer1 == nil && !firstMeasure.isInVisibleArea)
//if (measureBufferNil && !firstVisible)
{
//do some action
}
Update 1:
I isolated the problem to !firstMeasure.isInVisibleArea as I've entirely taken on the measureBuffer bit.
Inside isInVisible area is a small calculation (it doesn't modify anything though), but the calculation is using self.view.frame. I am going take this out of the equation as well and see what happens. My hunch is that self.view.frame is changing between the two calls to isInVisibleArea.
Update 2:
This is indeed the problem. I have added the answer in more detail below
When in doubt, you should fully parenthesize. Without looking up the precedence rules, what I think what is happening is that = is getting higher precedence than == or &&. So try:
BOOL test1 = ((measureBuffer1 == nil) && !firstMeasure.isInVisibleArea);
While you certainly can parenthesize, you should also know that nil objects evaluate to boolean NO and non-nil objects evaluate to boolean YES. So you could just as easily write this:
BOOL firstVisible = firstMeasure.isInVisibleArea;
BOOL notFirstVisible = !(firstMeasure.isInVisibleArea);
BOOL measureBufferNil = measureBuffer1;
BOOL test1 = !measureBuffer1 && !firstMeasure.isInVisibleArea;
BOOL test2 = measureBufferNil && !firstVisible;
if (measureBuffer1 && !firstMeasure.isInVisibleArea) {
//do some action
}
You would end up with the same results. I agree with GoatRider, though. It's always far better to parenthesize your conditional expressions to clarify what you really want to happen than it is to rely on the language's operator precedence to do it for you.
If test1 is evaluating to NO as you say, then drop test1 into the if statement:
if(test1){
//see if this executes?
}
See what that does.
My hunch was correct, it is related to the view frame changing between calls to firstMeasure.isInVisible area.
This whole routine is called in response to the view moving. I think I need to grab the value of firstMeasure.isInVisibleArea at the start of the method and use that value throughout.
Phew. Boolean logic isn't broken. All is right with the world.
Thanks for all your input