refer to Addison Wesley - Programming.in.ObjectiveC.2.0.2nd (2009)
#import <Foundation/NSObject.h>
#import <Foundation/NSArray.h>
#import <Foundation/NSString.h>
#import <Foundation/NSAutoreleasePool.h>
#import <Foundation/NSValue.h>
#define MAXPRIME 50
int main (int argc, char *argv[])
{
int i, p, prevPrime;
BOOL isPrime;
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
// Create an array to store the prime numbers
NSMutableArray *primes = [NSMutableArray arrayWithCapacity: 20];
// Store the first two primes (2 and 3) into the array
[primes
addObject: [NSNumber numberWithInteger: 2]]
//2是第一個公因數
[primes
addObject: [NSNumber numberWithInteger: 3]];
//3是第二個公因數
// Calculate the remaining primes
for (p = 5; p <= MAXPRIME; p += 2) {
// we ’ re testing to see if p is prime
isPrime = YES;
i = 1;
do {
//把公因數依序拿出來
prevPrime = [[primes
objectAtIndex: i] integerValue];
if (p % prevPrime == 0)
//可以整除的就不是公因數
isPrime = NO;
++i;
//找下一個公因數
} while ( isPrime == YES && p / prevPrime >= prevPrime);
if (isPrime)
//找到公因數就把它放到primes這個array內
[primes
addObject: [NSNumber numberWithInteger: p]];
//換下一個數字, 直到結束
}
// Display the results
for (i = 0; i < [primes count]; ++i)
//將所有的公因數依序印出
NSLog (@ ” %li ” , (long) [[primes
objectAtIndex: i] integerValue]);
[pool drain];
return 0;
}
在讀取所有的array時，有一個非常方便的方法
id item
for (item in primes)
{
}
參考資料區 http://blog.xuite.net/ray00000test/blog/29036653
NSArray與NSMutableArray與NSMutableDictionary
NSArray:固定長度陣列
使用固定一串資料給NSArray時，必須在陣列最後一個值放入nil，否則會發生錯誤。
範例：
NSArray *array = [ [ NSArray alloc ] initWithObjects:@"aa",@"bbb",nil];//宣告一陣列放入aa、bb字串
NSLog(@"array count==%d",array.count);//印出陣列長度
for(int i = 0; i < array.count; i++){//取出陣列裡的字串並印出來
NSLog(@"i=%@",[array objectAtIndex:i]);
}
[array release];//此陣列為暫存，且之後沒用到所以就將陣列從記憶體釋放
=====================================================================================
NSMutableArray:動態陣列
可以不斷放入物件的陣列，陣列長度隨著放入的物件變動
靜態宣告陣列時，一樣必須在陣列最後一個值放入nil，否則會發生錯誤。
範例1 (動態新增)：
NSMutableArray *array = [[NSMutableArray alloc]init];
[array addObject:@"aa"];
[array addObject:@"bbb"];
NSLog(@"array count==%d",array.count);
for(int i = 0; i < array.count; i++){
NSLog(@"i=%@",[array objectAtIndex:i]);
}
[array release];
範例2 (靜態放入值+動態新增)
NSMutableArray *array = [[NSMutableArray alloc]initWithObjects:@"cc",@"ddd",nil];
[array addObject:@"aa"];
[array addObject:@"bbb"];
NSLog(@"array count==%d",array.count);
for(int i = 0; i < array.count; i++){
NSLog(@"i=%@",[array objectAtIndex:i]);
}
[array release];
範例3 指定index放入物件,使用insertObject指定位置時，指定的位置必須是 (陣列長度 - 1) 以內的範例值
NSMutableArray *array = [[NSMutableArray alloc]initWithObjects:@"cc",@"ddd",nil];
[array addObject:@"aa"];
[array addObject:@"bbb"];
[array insertObject:@"aaaa" atIndex:4]; //在位置4放入 字串 aaaa
範例4:移除物件
移除指定位置物件
[array removeObjectAtIndex:4];
清除所有物件
[array removeAllObjects];
範例5:將數值放入陣列
int percentage = 40;
// 產生一個NSNumber物件，可以用signed or unsigned char, short int, int, long int, long long int, float, double or BOOL等基本型態產生物件
NSNumber *percentageObject = [NSNumber numberWithFloat:percentage];
//將NSNumber物件放入array
NSMutableArray *array = [[NSMutableArray alloc]init];
[array addObject:percentageObject];
//取出數值
[percentageObject intValue];
範例6:將指定位置的物件替換掉==>replaceObjectAtIndex:索引值(int) withObject:物件(id)
NSMutableArray *array = [[NSMutableArray alloc]initWithObjects:@"cc",@"ddd",nil];
[array addObject:@"aa"];
[array addObject:@"bbb"];
for(int i = 0; i < array.count; i++){
NSLog(@"i=%@",[array objectAtIndex:i]);
}
[array replaceObjectAtIndex:2 withObject:@"111"];
for(int i = 0; i < array.count; i++){
NSLog(@"i=%@",[array objectAtIndex:i]);
}
[array release];
NSDictionary及NSMutableDictionary(與java的Hashtable相似
============================================================
NSDictionary
及NSMutableDictionary兩種，兩者合稱字典(dictionary)，Mutable--善變的--表示可以
變，NSDictionary則像是constant。NSMutableDictionary是NSDictionary的subClass。這就像一
本字典，概念是(key, value)，用key來搜尋出所需的value。
NSDictionary：
initWithObjectsAndKeys：
NSDictionary
*dictionary = [[NSDictionary alloc] initWithObjectsAndKeys: @"one",
[NSNumber numberWithInt: 1], @"two",[NSNumber numberWithInt: 3], nil];
-(id) initWithObjectsAndKeys:(id) firstObject, ....
.....
第一個是firstObject的key，接著是secondObject、key，之後即為object、key的配對，直到出現nil為止。
注意：事實上nil一定出現在object的位置。若key是nil，會產生NSInvalidArgumentException。
NSMutableDictionary：
objectForKey：以下的key是由key = [objectOfNSEnumerator nextObject]; 產生的
[[[objectOfNSMutableDictionary objectForKey:key ] description] cString]；
setObject: forKey：[mutable setObject:@"Tom" forKey:@"tom@jones.com"];
範例1: 利用NSEnumerator 取出NSMutableDictionary陣列裡所有的物件，
(1):取得所有value
NSMutableDictionary *taiStyle = [[NSMutableDictionary alloc]init];
//所有台型字串
[taiStyle setObject:[[NSNumber alloc] initWithInt:1] forKey:@"102"]; //
[taiStyle setObject:[[NSNumber alloc] initWithInt:1] forKey:@"103"]; //
NSEnumerator *enumerator = [taiStyle objectEnumerator];
id value;
while ((value = [enumerator nextObject])) {
NSLog(@"%i",[((NSNumber*)value) intValue]);
}
(2):取得所有key
NSMutableDictionary *taiStyle = [[NSMutableDictionary alloc]init];
//所有台型字串
[taiStyle setObject:[[NSNumber alloc] initWithInt:1] forKey:@"102"]; //
[taiStyle setObject:[[NSNumber alloc] initWithInt:1] forKey:@"103"]; //
NSEnumerator *enumerator = [taiStyle keyEnumerator];
id key;
while ((key = [enumerator nextObject])) {
NSLog(@"%@",((NSString*)key));
}
範例2:
(1)用key取出value物件,使用 valueForKey: key ，若使入的key找不到對應的key，會回傳nil
[[NSMutableDictionary *taiStyle = [[NSMutableDictionary alloc]init];
//所有台型字串
[taiStyle setObject:[[NSNumber alloc] initWithInt:1] forKey:@"102"]; //
[taiStyle setObject:[[NSNumber alloc] initWithInt:1] forKey:@"103"]; //
NSString *key = @"102";
NSNumber *vlaue = [taiStyle valueForKey:key];
NSLog(@"%i",[vlaue intValue] );
(2)指定key移除對應的key與value物件
[taiStyle removeObjectForKey:@"102"];//移除以@"102"字串當key的物件，key也會被移除
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