1.数组的特点：
1）可以储存多个数据；
2）储存的多个数据的类型要相同；
3）储存在数组中的数据非常方便管理；
2.什么时候使用数组
当我们有多个类型相同的数据，并且这些数据的意义是一样的，需要储存的时候，就可以使用数组；
=================== NSArray ====================
Ordered collection of objects. Immutable(you cannot add or remove objects to it once it’s created)Important methods:+ (id)arrayWithObjects:(id)firstObject, ...; // nil terminated - (int)count; // 得到array中的对象个数- (id)objectAtIndex:(int)index; // 得到索引为i的对象- (BOOL)containsObject:(id)anObject; // 当anObject出现在array中，则返回yes（实际是通过isEqual:方法来判断）- (unsigned)indexOfObject:(id)anObject; // 查找array中的anObject,并返回其最小索引值。没找到返回NSNotFound.- (void)makeObjectsPerformSelector:(SEL)aSelector;- (NSArray *)sortedArrayUsingSelector:(SEL)aSelector;- (id)lastObject; // 得到array中最后一个对象。如果array中没有任何对象存在，则返回nil注：类方法arrayWithObjects 可以创建an autoreleased NSArray of the items.例如@implementation MyObject- (NSArray *)coolCats { return [NSArray arrayWithObjects:@“Steve”, @“Ankush”, @“Sean”, nil];}@endOther convenient create with methods (all return autoreleased objects):[NSString stringWithFormat:@“Meaning of %@ is %d”, @“life”, 42];[NSDictionary dictionaryWithObjectsAndKeys:ankush, @“TA”, janestudent, @“Student”, nil];[NSArray arrayWithContentsOfFile:(NSString *)path];-----创建数组 ----- NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil]; self.dataArray = array; [array release];NSLog(@"self.dataArray count is:%d",[self.dataArray count]);
NSLog(@"self.dataArray index 2 is:%@",[self.dataArray objectAtIndex:2]);
------ 从一个数组拷贝数据到另一数组(可变数级) -------
//arrayWithArray: NSArray *array1 = [[NSArray alloc] init]; NSMutableArray *MutableArray = [[NSMutableArray alloc] init]; NSArray *array = [NSArray arrayWithObjects:@"a",@"b",@"c",nil]; NSLog(@"array:%@",array); MutableArray = [NSMutableArray arrayWithArray:array]; NSLog(@"MutableArray:%@",MutableArray); array1 = [NSArray arrayWithArray:array]; NSLog(@"array1:%@",array1); //Copy //id obj; NSMutableArray *newArray = [[NSMutableArray alloc] init]; NSArray *oldArray = [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil]; NSLog(@"oldArray:%@",oldArray); for(int i = 0; i < [oldArray count]; i++) { obj = [[oldArray objectAtIndex:i] copy]; [newArray addObject: obj]; } NSLog(@"newArray:%@", newArray); [newArray release];//快速枚举
NSMutableArray *newArray = [[NSMutableArray alloc] init]; NSArray *oldArray = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil]; NSLog(@"oldArray:%@",oldArray); for(id obj in oldArray) { [newArray addObject: obj]; } NSLog(@"newArray:%@", newArray); [newArray release]; //Deep copy NSMutableArray *newArray = [[NSMutableArray alloc] init]; NSArray *oldArray = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil]; NSLog(@"oldArray:%@",oldArray); newArray = (NSMutableArray*)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (CFPropertyListRef)oldArray, kCFPropertyListMutableContainers); NSLog(@"newArray:%@", newArray); [newArray release];=================== NSMutableArray ====================
Mutable version of NSArray.- (void)addObject:(id)anObject; // 在array最后添加anObject, 添加nil是非法的.- (void)addObjectsFromArray:(NSArray *)otherArray; //在array最后把otherArray中的对象依次添加进去。- (void)insertObject:(id)anObject atIndex:(int)index; //在索引index处插入anObject, 若index被占用，会把之后的object向后移。- (void)removeObjectAtIndex:(int)index; //删除index处的对象，后面的对象依次向前移。- (void)removeObject:(id)anObject; // 删除所有和anObject相等的对象，同样使用isEqual:作为相等比较方法.- (void)removeAllObjects;注：我们不能把nil加到array中。但有时候我们真想给array加一个空的对象，可以使用NSNull来做这件事。如：[myArray addObject:[NSNull null]];-----给数组分配容量-----
//NSArray *array; array = [NSMutableArray arrayWithCapacity:20];-----在数组末尾添加对象----- //- (void) addObject: (id) anObject; //NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil]; [array addObject:@"Four"]; NSLog(@"array:%@",array);-----删除数组中指定索引处对象----- //-(void) removeObjectAtIndex: (unsigned) index; //NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil]; [array removeObjectAtIndex:1]; NSLog(@"array:%@",array);----- 数组枚举-----
//1、- (NSEnumerator *)objectEnumerator; //从前向后 NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil]; NSEnumerator *enumerator; enumerator = [array objectEnumerator]; id thingie; while (thingie = [enumerator nextObject]) { NSLog(@"thingie:%@",thingie); }//2、- (NSEnumerator *)reverseObjectEnumerator; //从后向前 NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil]; NSEnumerator *enumerator; enumerator = [array reverseObjectEnumerator]; id object; while (object = [enumerator nextObject]) { NSLog(@"object:%@",object); }//3、快速枚举 NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil]; for(NSString *string in array) { NSLog(@"string:%@",string); }
----- NSValue（对任何对象进行包装）-----
//将NSRect放入NSArray中 NSMutableArray *array = [[NSMutableArray alloc] init]; NSValue *value; CGRect rect = CGRectMake(0, 0, 320, 480); value = [NSValue valueWithBytes:&rect objCType:@encode(CGRect)]; [array addObject:value]; NSLog(@"array:%@",array);//从Array中 提取 value = [array objectAtIndex:0]; [value getValue:&rect]; NSLog(@"value:%@",value);----★使用NSMutableArray要防止内存泄露★------NSObject* p1 = [[NSObject alloc] init];NSObject* p2 = [[NSObject alloc] init];NSMutableArray* objectsArray = [[NSMutableArray alloc] init];[objectsArray addObject:p1];NSLog(@"p1 count:%d", [p1 retainCount]);//输出 2，也就是执行追加对象后，对象的计数器也被加1//[p1 release];//NSLog(@"p1 count:%d", [p1 retainCount]);//同样做数组替换时[objectsArray replaceObjectAtIndex:0 withObject:p2];NSLog(@"p2 count:%d", [p2 retainCount]);//输出 2，同样也是2NSLog(@"p1 count:%d", [p1 retainCount]);//输出 1，对象p1仍然存在//[p2 release];//NSLog(@"p2 count:%d", [p2 retainCount]);//执行清空数组[objectsArray removeAllObjects];NSLog(@"p2 count:%d", [p2 retainCount]);//输出 1，对象p2仍然存在//[p2 release];由此可知，每次执行上面的数组操作后，要执行对象release，如上面注释中的语句，才能保证内存不泄露。