New to Objective-C and trying to complete a final project for a class. I have created a method to set a date based on user input and am running into some trouble with the setter. User will first have to select option to add new entry and then program should ask user to enter a date and set date based on that input.
#import <Foundation/Foundation.h>
#interface Planner : NSObject {
NSNumber *date;
}
-(void) setDate:(NSNumber *)newDate;
-(NSNumber *) date;
#end
#implementation Planner
-(void) setDate:(NSNumber *) newDate
{
date = [[NSNumber alloc] initWithInt: newDate];
NSLog(#"Enter date");
scanf("%i", newDate);
}
-(NSNumber *) date;
{
return date;
}
#end
int main (int argc, const char * argv[])
{
int userAction;
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
Planner *newPlanner = [[Planner alloc] init];
NSLog(#"Please enter 1 to add a new entry and 2 to update an existing entry");
scanf("%i", userAction);
if (userAction == 1) {
[newPlanner setDate];
}
else
NSLog(#"will update");
[pool drain];
return 0;
}
-(void) setDate:(NSNumber *) newDate;
setDate is supposed to receive an argument of type NSNumber*. But you are calling the method with out passing any parameter.
[newPlanner setDate]; // [newPlanner setDate: shouldPassNSNumberArgument];
Like -
[newPlanner setDate:[NSNumber numberWithInt:10] ];
Related
Here's a little experiment:
#interface Model : NSObject
#property (copy) NSString *value;
-(instancetype)initWith:(NSString *)value;
#end
#implementation Model
-(instancetype)initWith:(NSString *)value {
self = [super init];
self.value = value;
return self;
}
#end
#import <Foundation/Foundation.h>
#import "Model.h"
void experiment(Model *m);
int main(int argc, const char * argv[]) {
#autoreleasepool {
// insert code here...
NSLog(#"Hello, World!");
Model *ma = [[Model alloc] initWith:[[NSUUID UUID] UUIDString]];
experiment(ma);
NSLog(#"yyy %#", [ma value]);
}
return 0;
}
void experiment(ModelA *m) {
NSString *testValue = nil;
testValue = [m value];
NSLog(#"xxx %#", testValue);
}
When run, this produces the following:
Hello, World!
xxx 6005A7B0-F71C-4755-B1BF-792D6296B716
yyy 6005A7B0-F71C-4755-B1BF-792D6296B716
Program ended with exit code: 0
But suppose I make this line:
testValue = [m value];
part of a breakpoint:
And this changes everything:
Hello, World!
(__NSCFString *) $0 = 0x000000010071e220 #"1C0DCB39-BFBB-4E67-A041-E6B58615BDFD"
xxx 1C0DCB39-BFBB-4E67-A041-E6B58615BDFD
yyy 1C0DCB39-BFBB-4E67-A041-E6B58615BDFD
*** -[CFString release]: message sent to deallocated instance 0x10071e220
And a crash. I see what's happening--the string is released once we exit the function scope, and the second time when the Model object is destroyed, which is an overrelease. But why doesn't the breakpoint (or more precisely, the lldb expression inside the breakpoint) handle the reference count correctly?
Am getting a "Missing context for method declaration" for my overridden description method. Can you tell what's wrong with the code?
#import <Foundation/Foundation.h>
#import "BNRItem.h"
int main(int argc, const char * argv[])
{
#autoreleasepool {
// Create a mutable array object, store its address in items variable
NSMutableArray *items = [[NSMutableArray alloc]init];
BNRItem *p = [[BNRItem alloc]init];
NSLog(#"%# %# %# %d", [p itemName], [p dateCreated], [p serialNumber], [p valueInDollars]);
// This creates a new NSString, "Red Sofa" and gives it to the BNRItem
[p setItemName:#"Red Sofa"];
// This creates a new NSString, "A1B2C" and gives it to the BNRItem
[p setSerialNumber:#"A1B2C"];
// We send the value 100 to be used as the valueInDollars of this BNRItem
[p setValueInDollars:100];
// Destroy the array pointed to by items
items = nil;
}
return 0;
}
-(NSString *)description // Missing context for method declaration
{
NSString *descriptionString =
[[NSString alloc]initWithFormat:#"%# (%#): Worth $%d, recorded on %#",
itemName;
serialNumber;
valueInDollars;
dateCreated];
return descriptionString;
}
BNRItem.m
#import "BNRItem.h"
#implementation BNRItem
-(void)setItemName:(NSString *)str {
itemName = str;
}
-(NSString *)itemName {
return itemName;
}
-(void)setSerialNumber:(NSString *)str {
serialNumber = str;
}
-(NSString *)serialNumber {
return serialNumber;
}
-(void)setValueInDollars:(int)i {
valueInDollars = i;
}
-(int)valueInDollars {
return valueInDollars;
}
-(NSDate *)dateCreated {
return dateCreated;
}
-(NSString *)description
{
NSString *descriptionString =
[[NSString alloc]initWithFormat:#"%# (%#): Worth $%d, recorded on %#",
itemName,
serialNumber; // Expected "]"
valueInDollars, // Expression result unused
dateCreated]; //Extraneous "]" before ";"
return descriptionString;
}
#end
Your method appears to be free floating inside main.m. An instance method needs to be placed inside the implementation section of a class. (between #implementation and #end).
My guess is that you should move that code into BNRItem.m.
If you have something like a char at the veryfirst beginning of your Header oder .m file, its also likely that this error accures.
^//
// EMServices.m
// MyController
//
// Created by EMart on 09.01.14.
// Copyright (c) 2014 EMart. All rights reserved.
//
So I presume this is a memory issue, here's the code:
- (NSString *)giveMeAStringGoddammit
{
NSString *s;
// switch statement to choose which string to assign to s, so essentially:
s = #"a string";
return s;
}
And the calling code:
NSString *aString;
aString = [self giveMeAStringGoddammit];
However after this call, aString has an invalid summary when debugged and crashes when run.
I suspect I'm missing a retain or something, can someone help? Thanks.
What you've got works just fine:
#import <Foundation/Foundation.h>
#interface Test : NSObject
- (NSString *)giveMeAStringGoddammit;
#end
#implementation Test
- (NSString *)giveMeAStringGoddammit
{
NSString *s;
// switch statement to choose which string to assign to s, so essentially:
s = #"a string";
return s;
}
#end
int main (int argc, const char * argv[])
{
#autoreleasepool {
Test *t = [[Test alloc] init];
NSLog(#"t says: %#", [t giveMeAStringGoddammit]);
}
return 0;
}
The output of this program is:
t says: a string
To make this a little more realistic, let's change it to use a property:
#import <Foundation/Foundation.h>
#interface Test : NSObject
#property(copy, nonatomic) NSString *string;
- (NSString *)giveMeAStringGoddammit;
#end
#implementation Test
#synthesize string;
- (NSString *)giveMeAStringGoddammit
{
NSString *s;
// switch statement to choose which string to assign to s, so essentially:
s = self.string;
return s;
}
#end
int main (int argc, const char * argv[])
{
#autoreleasepool {
Test *t = [[Test alloc] init];
t.string = #"Hello world!";
NSLog(#"t says: %#", [t giveMeAStringGoddammit]);
}
return 0;
}
This does what you'd expect:
t says: Hello world!
You have created a pointer object and it's expected to increment it's retain count whenever you referring them, for increasing retain count the string should be initiated and allocated with memory else you could use [NSString stringwithString:[self giveMeAStringGoddammit]. You can use this definition only when you exactly need it reference locally. because whenever you try to refer it out side the auto release pool will crash the app (hence it's not retained manually). So if you need to use it out side of the function, better use [NSString alloc]init] and then load your string to the pointer object. Well the way to make your code to work is add the lines NSString *aString = [NSString stringWithString:[self giveMeAStringGoddammit]];
NSLog(#"My Str:%#",aString); Hooray now the goddammit string was given......
I could not able to get the value for the key.
I have a structure pt(which is the value) and a wTiId,wTiId1(which is the key).
I am sure that something wrong i'm doing in the below code but i could not figure out what
it is.
Timers.h
---------
#import <Foundation/Foundation.h>
struct session {
int a;
char c;
}pstruct;
#interface Timers : NSObject {
unsigned short wTiId;
unsigned short wTiId1;
}
-(void)timer;
#end
Timers.m
--------
#import "Timers.h"
#implementation Timers
-(id)init
{
if (self=[super init]) {
wTiId=71;
wTiId1=72;
}
return self;
}
-(void)dealloc
{
[super dealloc];
}
-(void)timer
{
struct session* pt = &pstruct;
pt->a=12;
pt->c='L';
CFDictionaryValueCallBacks cbvs = {0,NULL,NULL,NULL,NULL};
CFMutableDictionaryRef cfmdict = CFDictionaryCreateMutable(NULL,0,&kCFTypeDictionaryKeyCallBacks,&cbvs);
NSLog(#"Dict size:%d\n",((CFIndex)CFDictionaryGetCount(cfmdict)));
CFNumberRef tiId = CFNumberCreate(NULL,kCFNumberShortType,&wTiId);
CFNumberRef tiId1 = CFNumberCreate(NULL,kCFNumberShortType,&wTiId1);
CFDictionarySetValue(cfmdict,tiId,pt);
NSLog(#"Dict size:%d\n",((CFIndex)CFDictionaryGetCount(cfmdict)));
CFDictionarySetValue(cfmdict,tiId1,pt);
NSLog(#"Dict size:%d\n",((CFIndex)CFDictionaryGetCount(cfmdict)));
NSLog(#"The value is:%s",(CFDictionaryGetValue(cfmdict,tiId)));
CFRelease(tiId);
CFRelease(tiId1);
}
#end
main.m
------
#import <Foundation/Foundation.h>
#import "Timers.h"
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
Timers* time = [[Timers alloc]init];
[time timer];
[pool drain];
return 0;
}
output
------
2011-05-15 14:52:54.857 timer[3511:a0f] Dict size:0
2011-05-15 14:52:54.861 timer[3511:a0f] Dict size:1
2011-05-15 14:52:54.861 timer[3511:a0f] Dict size:2
2011-05-15 14:52:54.862 timer[3511:a0f] The value is:
I tried with the format specifier "%#" also.Nothing gets printed when CFDictionaryGetValue
() function is called.The return type of this function is const void*.
The result of CFDictionaryGetValue is what you put in the dictionary.
You have to cast the result of CFDictionaryGetValue to the right pointer type to access the structure members:
struct session *value = (struct session *) CFDictionaryGetValue(cfmdict,tiId);
NSLog(#"The value is %d and %c", value->a, value->c);
You cannot store structs in CFDictionarys, only pointers to structs will work. You cannot print the contents of the struct with the %s format specifier.
#import "movie.h"
int main (int argc, const char * argv[])
{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
// insert code here...
movie *obj = [[movie alloc]init];
[obj findinterestofnum1:(int)200 num2:(int)4 num3:(int)5];
SEL suf = #selector(findinterestofnum1: num2:num3:);
BOOL sul = [obj respondsToSelector:suf];
if(sul)
{
NSLog(#"It is implememted");
}
else
{
NSLog(#" It is not implemented");
}
NSLog(#"Hello, World!");
[pool drain];
return 0;
}
********-----
#interface movie : NSObject {
#private
}
-(void)findinterestofnum1:(int)p num2:(int)n num3:(int)r;
#end
*******-------
#import "movie.h"
#implementation movie
-(void)findinterestofnum1:(int)p num2:(int)n num3:(int)r
{
int a ;
a= (p*n*r/100);
NSLog(#"interest value is =%d",a);
}
- (void)dealloc
{
[super dealloc];
}
#end
i am trying to find whether method is implemented and if it is not it should print it is not implemented
#toddler, respondsToSelector just checks if the corresponding object can respond to that particular method. It doesn't do any checks on whether interface has that definition associated with it since it is a runtime check.
If you had removed the code from the implementation file (.m file) and not the interface, you would have got an error while executing it and you would have found that the BOOL sul is FALSE.