[BS-02] iOS數組、字典、NSNumber 新寫法—— @[]、@{}

IOS數組、字典、NSNumber 新寫法—— @[]、@{}

 

//標准寫法
NSNumber * number = [NSNumber numberWithInt:1]; 
NSArray * array = [NSArray arrayWithObjects:@"one", @"two", nil]; 
NSDictionary * dict = [NSDictionary dictionaryWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil]; 


//快捷寫法
NSNumber * number = @1; 
NSArray * array = @[@"one", @"two"]; 
NSDictionary * dict = @{@"key1":@"value1", @"key2":@"value2"}; 

NSMutableArray *m_array = [@[] mutableCopy]; 
NSMutableDictionary *m_dict = [@{} mutableCopy]; 

 

WWDC2012大會上介紹了大量Objective-C的新特性，能夠幫助iOS程序員更加高效地編寫代碼。在XCode4.4版本中可以使用以下特性：

一. 
Object Literals這個是我認為最贊的一個改進。Object Literals允許你方便地定義數字、數組和字典對象。這個功能類似於java5提供的auto boxing功能。這雖然是一個語法糖，但我認為對提高寫代碼效率幫助很大。讓我們先來看看以前定義數字、數組和字典對象的方法：

1  NSNumber * number = [NSNumber numberWithInt:1];
2  NSArray * array = [NSArray arrayWithObjects:@"one", @"two", nil];
3  NSDictionary * dict = [NSDictionary dictionaryWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil];

是不是很惡心？現在以上代碼可以簡化成以下形式，注意到沒有，不用再在參數的最后加惡心的nil了，字典的key和value也不再是倒着先寫value,再寫key了：
1  NSNumber * number = @1;
2  NSArray * array = @[@"one", @"two"];
3  NSDictionary * dict = @{@"key1":@"value1", @"key2":@"value2"};

更多的示例如下：

1  // 整數
2  NSNumber *fortyTwo = @42;             // 等價於 [NSNumber numberWithInt:42]
3  NSNumber *fortyTwoUnsigned = @42U;    // 等價於 [NSNumber numberWithUnsignedInt:42U]
4  NSNumber *fortyTwoLong = @42L;        // 等價於 [NSNumber numberWithLong:42L]
5  NSNumber *fortyTwoLongLong = @42LL;   // 等價於 [NSNumber numberWithLongLong:42LL]
6
7  // 浮點數
8  NSNumber *piFloat = @3.141592654F;    // 等價於 [NSNumber numberWithFloat:3.141592654F]
9  NSNumber *piDouble = @3.1415926535;   // 等價於 [NSNumber numberWithDouble:3.1415926535]
10
11  // 布爾值
12  NSNumber *yesNumber = @YES;           // 等價於 [NSNumber numberWithBool:YES]
13  NSNumber *noNumber = @NO;             // 等價於 [NSNumber numberWithBool:NO]
14
15  // 空數組
16  NSArray * array = @[];                // 等價於 [NSArray array]
17  // 空的字典
18  NSDictionary * dict = @{};            // 等價於 [NSDictionary dictionary]

怎么樣？是不是簡單多了？而且，為了方便你的舊代碼遷移到新的寫法，xcode專門還提供了轉換工具，在xcode4.4中，選擇 Edit -> Refactor -> Convert to Modern Objective-C Syntax即可。

二. 
在XCode4.5中實現了一個很體貼的語法，它允許你使用中括號[]來代替原本的方法來獲取get和設置set數組/字典元素。

簡單來說，以前的 [array objectAtIndex:idx] 和 [array replaceObjectAtIndex:idx withObject:obj]，可以直接寫作 array[idx] 和 array[idx] = obj了。其實這個特性在很多高級語言中都實現了，只是Objective-C生於80年代，一直沒改進這個。

使用【】訪問數組、字典，使用@()作為計算表達式
1  NSArray * array = @[ @"111", @"222", @"333"];
2  for (int i = 0; i < 3; ++i) {
3      NSLog(@"array[i] = %@", array[i]);
4  }
5  
6  NSMutableDictionary * dict =[@{  @1: @"value1",
7                                   @2: @"value2",
8                                   @3: @"value3" } mutableCopy];
9  for (int i = 0; i < 3; ++i) {
10      NSLog(@"dict[%d] = %@", i, dict[@(i+1)]); //@()是計算表達式
11      dict[@(i+1)] = [NSString stringWithFormat:@"new %@", dict[@(i+1)]];
12  }
13  
14  [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
15      NSLog(@"dict[%@] = %@", key, dict[key]);
16  }];

使用【】對可變數組和可變字典設值：
NSMutableArray *arrayM = [NSMutableArray array];
//NSMutableArray * arrayM = @[ @"111" mutableCopy];//從不可變數組創建可變數組
array[0] = @"123";
array[1] = @"456";

NSMutableDictionary *dictM = [NSMutableDictionary dictionary];
dictM[@"1"] = @"abc";
dictM[@"2"] = @"xyz";

三、遍歷元素

你是如何遍歷數組的元素的？通常我們有2種做法，一種是用 for in，另一種是用一個變量來循環數組下標。如下：
1    NSArray * array = @[@"123",@"abc",@"xyz"];
2    for (NSString * str in array) {
3       // ...
4    }
5    for (int i = 0; i < array.count; ++i) {
6        NSString * str = [array objectAtIndex:i];
7        ...
8    }

如果是字典，遍歷的代碼就要稍微復雜一點了：
1    NSDictionary * dict = @{@"1":@"abc",@"2":@"xyz"};
2    NSArray * keys = [dict allKeys];
3    for (NSString * key in keys) {
4        NSString * value = [dict objectForKey:key];
5    }
現在，xcode對於iOS4.0以上的系統，支持用block來遍歷元素了。用block來遍歷字典可以簡化代碼的編寫，建議大家都使用上這個新特性。
1 [array enumerateObjectsUsingBlock:^(NSString * obj, NSUInteger idx, BOOL *stop) {
2 
3 }];

4 
5 [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
6 
7 }];

 

 

//  ios 字符串 數組 字典 常用方法

/*
NSString
*/
//一、NSString
/----------------創建字符串的方法----------------/

//1、創建常量字符串。
NSString *astring = @"This is a String!";

//2、創建空字符串，給予賦值。

NSString *astring = [[NSString alloc] init];
astring = @"This is a String!";
[astring release];
NSLog(@"astring:%@",astring);

//3、在以上方法中，提升速度:initWithString方法

NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
[astring release];

//4、用標准c創建字符串:initWithCString方法

char Cstring = "This is a String!";
NSString astring = [[NSString alloc] initWithCString:Cstring];
NSLog(@"astring:%@",astring);
[astring release];

//5、創建格式化字符串:占位符（由一個%加一個字符組成）

int i = 1;
int j = 2;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
NSLog(@"astring:%@",astring);
[astring release];

//6、創建臨時字符串

NSString *astring;
astring = [NSString stringWithCString:"This is a temporary string"];
NSLog(@"astring:%@",astring);

/----------------從文件讀取字符串:initWithContentsOfFile方法----------------/

NSString path = @"astring.text";
NSString astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];

/----------------寫字符串到文件:writeToFile方法----------------/

NSString astring = [[NSString alloc] initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
NSString path = @"astring.text";
[astring writeToFile: path atomically: YES];
[astring release];

/----------------比較兩個字符串----------------/

//用C比較:strcmp函數

char string1[] = "string!";
char string2[] = "string!";
if(strcmp(string1, string2) = = 0)
{
NSLog(@"1");
}

//isEqualToString方法
NSString astring01 = @"This is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@"result:%d",result);

//compare方法(comparer返回的三種值)
NSString astring01 = @"This is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedSame判斷兩者內容是否相同

NSString astring01 = @"This is a String!";
NSString astring02 = @"this is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
NSLog(@"result:%d",result);
//NSOrderedAscending判斷兩對象值的大小(按字母順序進行比較，astring02大於astring01為真)

NSString astring01 = @"this is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;
NSLog(@"result:%d",result);
//NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01為真)

//不考慮大小寫比較字符串1
NSString astring01 = @"this is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01為真)

//不考慮大小寫比較字符串2
NSString astring01 = @"this is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02
options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;
NSLog(@"result:%d",result);

//NSCaseInsensitiveSearch:不區分大小寫比較 NSLiteralSearch:進行完全比較，區分大小寫 NSNumericSearch:比較字符串的字符個數，而不是字符值。

/----------------改變字符串的大小寫----------------/

NSString string1 = @"A String";
NSString string2 = @"String";
NSLog(@"string1:%@",[string1 uppercaseString]);//大寫
NSLog(@"string2:%@",[string2 lowercaseString]);//小寫
NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小

/----------------在串中搜索子串----------------/

NSString string1 = @"This is a string";
NSString string2 = @"string";
NSRange range = [string1 rangeOfString:string2];
int location = range.location;
int leight = range.length;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
NSLog(@"astring:%@",astring);
[astring release];

/----------------抽取子串 ----------------/

//-substringToIndex: 從字符串的開頭一直截取到指定的位置，但不包括該位置的字符
NSString string1 = @"This is a string";
NSString string2 = [string1 substringToIndex:3];
NSLog(@"string2:%@",string2);

//-substringFromIndex: 以指定位置開始（包括指定位置的字符），並包括之后的全部字符
NSString string1 = @"This is a string";
NSString string2 = [string1 substringFromIndex:3];
NSLog(@"string2:%@",string2);

//-substringWithRange: //按照所給出的位置，長度，任意地從字符串中截取子串
NSString string1 = @"This is a string";
NSString string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
NSLog(@"string2:%@",string2);

//擴展路徑

NSString Path = @"~/NSData.txt";
NSString absolutePath = [Path stringByExpandingTildeInPath];
NSLog(@"absolutePath:%@",absolutePath);
NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);

//文件擴展名
NSString *Path = @"~/NSData.txt";
NSLog(@"Extension:%@",[Path pathExtension]);

/*
NSMutableString
*/

/---------------給字符串分配容量----------------/
//stringWithCapacity:
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];

/---------------在已有字符串后面添加字符----------------/

//appendString: and appendFormat:

NSMutableString String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
//[String1 appendString:@", I will be adding some character"];
[String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
NSLog(@"String1:%@",String1); /

/--------在已有字符串中按照所給出范圍和長度刪除字符------/
/
//deleteCharactersInRange:
NSMutableString String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];
NSLog(@"String1:%@",String1);

/--------在已有字符串后面在所指定的位置中插入給出的字符串------/

//-insertString: atIndex:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 insertString:@"Hi! " atIndex:0];
NSLog(@"String1:%@",String1);

/--------將已有的空符串換成其它的字符串------/

//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 setString:@"Hello Word!"];
NSLog(@"String1:%@",String1);

/--------按照所給出的范圍，和字符串替換的原有的字符------/

//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
NSLog(@"String1:%@",String1);

/-------------判斷字符串內是否還包含別的字符串(前綴，后綴)-------------/
//01：檢查字符串是否以另一個字符串開頭- (BOOL) hasPrefix: (NSString ) aString;
NSString String1 = @"NSStringInformation.txt";
[String1 hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
[String1 hasSuffix:@".txt"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");

//02：查找字符串某處是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString，這一點前面在串中搜索子串用到過;

/*
NSArray
*/

/---------------------------創建數組------------------------------/
//NSArray *array = [[NSArray alloc] initWithObjects:
@"One",@"Two",@"Three",@"Four",nil];

self.dataArray = array;
[array release];

//- (unsigned) Count;數組所包含對象個數；
NSLog(@"self.dataArray cound:%d",[self.dataArray count]);

//- (id) objectAtIndex: (unsigned int) index;獲取指定索引處的對象;
NSLog(@"self.dataArray cound 2:%@",[self.dataArray objectAtIndex:2]);

/--------------------------從一個數組拷貝數據到另一數組(可變數級)----------------------------/

//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];

//快速枚舉

//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];

//Copy and sort

//NSMutableArray newArray = [[NSMutableArray alloc] init];
NSArray oldArray = [NSArray arrayWithObjects:
@"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];
NSLog(@"oldArray:%@",oldArray);
NSEnumerator *enumerator;
enumerator = [oldArray objectEnumerator];
id obj;
while(obj = [enumerator nextObject])
{
[newArray addObject: obj];
}
[newArray sortUsingSelector:@selector(compare:)];
NSLog(@"newArray:%@", newArray);
[newArray release];

/---------------------------切分數組------------------------------/

//從字符串分割到數組－ componentsSeparatedByString:
NSString string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];
NSLog(@"string:%@",string);
NSArray array = [string componentsSeparatedByString:@","];
NSLog(@"array:%@",array);
[string release];

//從數組合並元素到字符串- componentsJoinedByString:
NSArray array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSString string = [array componentsJoinedByString:@","];
NSLog(@"string:%@",string);

/*
NSMutableArray
*/
/---------------給數組分配容量----------------/
//NSArray *array;
array = [NSMutableArray arrayWithCapacity:20];

/--------------在數組末尾添加對象----------------/
//- (void) addObject: (id) anObject;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
[array addObject:@"Four"];
NSLog(@"array:%@",array);

/--------------刪除數組中指定索引處對象----------------/
//-(void) removeObjectAtIndex: (unsigned) index;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
[array removeObjectAtIndex:1];
NSLog(@"array:%@",array);

/-------------數組枚舉---------------/
//- (NSEnumerator )objectEnumerator;從前向后
//NSMutableArray array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array objectEnumerator];

id thingie;
while (thingie = [enumerator nextObject]) {
NSLog(@"thingie:%@",thingie);
}

//- (NSEnumerator )reverseObjectEnumerator;從后向前
//NSMutableArray array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array reverseObjectEnumerator];

id object;
while (object = [enumerator nextObject]) {
NSLog(@"object:%@",object);
}

//快速枚舉
//NSMutableArray array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
for(NSString string in array)
{
NSLog(@"string:%@",string);
}

/*
NSDictionary
*/

/------------------------------------創建字典------------------------------------/
//- (id) initWithObjectsAndKeys;

//NSDictionary dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];
NSString string = [dictionary objectForKey:@"One"];
NSLog(@"string:%@",string);
NSLog(@"dictionary:%@",dictionary);
[dictionary release];

/*
NSMutableDictionary
*/

/------------------------------------創建可變字典------------------------------------/
//創建
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];

//添加字典
[dictionary setObject:@"One" forKey:@"1"];
[dictionary setObject:@"Two" forKey:@"2"];
[dictionary setObject:@"Three" forKey:@"3"];
[dictionary setObject:@"Four" forKey:@"4"];
NSLog(@"dictionary:%@",dictionary);

//刪除指定的字典
[dictionary removeObjectForKey:@"3"];
NSLog(@"dictionary:%@",dictionary);

/*
NSValue（對任何對象進行包裝）
*/

/--------------------------------將NSRect放入NSArray中------------------------------------/
//將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);

//從Array中提取
value = [array objectAtIndex:0];
[value getValue:&rect];
NSLog(@"value:%@",value);

/*
從目錄搜索擴展名為jpg的文件
*/

//NSFileManager fileManager = [NSFileManager defaultManager];
NSString home;
home = @"../Users/";

NSDirectoryEnumerator *direnum;
direnum = [fileManager enumeratorAtPath: home];

NSMutableArray *files = [[NSMutableArray alloc] init];

//枚舉
NSString *filename;
while (filename = [direnum nextObject]) {
if([[filename pathExtension] hasSuffix:@"jpg"]){
[files addObject:filename];
}
}

//快速枚舉
//for(NSString *filename in direnum)
//{
// if([[filename pathExtension] isEqualToString:@"jpg"]){
// [files addObject:filename];
// }
//}
NSLog(@"files:%@",files);

//枚舉
NSEnumerator *filenum;
filenum = [files objectEnumerator];
while (filename = [filenum nextObject]) {
NSLog(@"filename:%@",filename);
}

//快速枚舉
//for(id object in files)
//{
// NSLog(@"object:%@",object);
//}