一、NSString
创建字符串。
- NSString *astring = @"This is a String!";
创建空字符串,给予赋值。
- NSString *astring = [[NSString alloc] init];
- astring = @"This is a String!";
- NSLog(@"astring:%@",astring);
- string release];
使用变量初始化
- NSString *name = @"Ivan!";
- NSString *astring = [[NSString stringWithFormat:@”My name is %@!”,name]];
- NSLog(@"astring:%@",astring);
判断是否包含某字符串
检查字符串是否以另一个字符串开头
- - (BOOL) hasPrefix: (NSString *) aString;
- NSString *String1 = @"NSStringInformation.txt";
- [String1 hasPrefix:@"NSString"] == 1 ? NSLog(@"YES") : NSLog(@"NO");
- [String1 hasSuffix:@".txt"] == 1 ? NSLog(@"YES") : NSLog(@"NO");
是否包含其它字符
- NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
- Boolean contains = [astring rangeOfString:@”This”].length>0;
从文件读取字符串:
- initWithContentsOfFile方法
- NSString *path = @"astring.text";
- NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
- NSLog(@"astring:%@",astring);
- [astring release];
写字符串到文件: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];
比较两个字符串
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返回的三种值)
- NSString *astring01 = @"This is a String!";
- NSString *astring02 = @"This is a String!";
- BOOL result = [astring01 compare:astring02] = = NSOrderedSame;
- NSLog(@"result:%d",result);
NSOrderedSame判断两者内容是否相同
- NSString *astring01 = @"This is a String!";
- NSString *astring02 = @"this is a String!";
- BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
- NSLog(@"result:%d",result);
不考虑大小写比较字符串1
- NSString *astring01 = @"this is a String!";
- NSString *astring02 = @"This is a String!";
- BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
- NSLog(@"result:%d",result);
改变字符串的大小写
- NSString *string1 = @"A String";
- NSString *string2 = @"String";
- NSLog(@"string1:%@",[string1 uppercaseString]);//大写
- NSLog(@"string2:%@",[string2 lowercaseString]);//小写
- 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];
替换字符串
- NSString *astring01 = @"hello 中国";
- NSString * new = [astring01 stringByReplacingOccurrencesOfString:@”中国” withString:@"北京"];
- NSLog(new);
分割字符串成数组
- NSString *s = @"a b d e f";
- NSArray *arr = [s componentsSeparatedByString:@" "];
- NSLog(@"count = %d",[arr count]);
字符串数组拼接成字符串
- NSArray *pathArray = [NSArray arrayWithObjects:@"here",
- @"be", @"dragons", nil];
- NSLog(@"%@",[pathArray componentsJoinedByString:@""]);
抽取子串
-substringToIndex: 从字符串的开头一直截取到指定的位置,但不包括该位置的字符
- NSString *string1 = @"This is a string";
- NSString *string2 = [string1 substringToIndex:3];
- NSLog(@"string2:%@",string2);
-substringFromIndex: 以指定位置开始(包括指定位置的字符),并包括之后的全部字符
- NSString *string1 = @"This is a string";
- NSString *string2 = [string1 substringFromIndex:3];
- NSLog(@"string2:%@",string2);
-substringWithRange: //按照所给出的位置,长度,任意地从字符串中截取子串
- NSString *string1 = @"This is a string";
- NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
- NSLog(@"string2:%@",string2);
二、NSMutableString
给字符串分配容量
- //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给出范围和长度删除字符
- //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给出的字符串
- //-insertString: atIndex:
- NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
- [String1 insertString:@"Hi! " atIndex:0];
- NSLog(@"String1:%@",String1);
将已有的换成其它的字符串
- //-setString:
- NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
- [String1 setString:@"Hello Word!"];
- NSLog(@"String1:%@",String1);
按照所给出的范围,和字符串替换的原有的字符
- //-setString:
- NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
- [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
- NSLog(@"String1:%@",String1);
三、NSArray
创建数组
- NSArray *array = [[NSArray alloc] initWithObjects:
- @"One",@"Two",@"Three",@"Four",nil];
- self.dataArray = array;
- [array release];
- //- (unsigned) Count;数组所包含对象个数;
- NSLog(@"self.dataArray cound:%d",[self.dataArray count]);
- //获取指定索引处的对象
- NSLog(@"self.dataArray cound 2:%@",[self.dataArray objectAtIndex:2]);
从一个数组拷贝数据到另一数组
- //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];
快速遍历数组
- //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];
- 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];
- NSMutableArray
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
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);
- }
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);
- }
快速枚举
- //NSMutableArray *array = [NSMutableArray arrayWithObjects:
- @"One",@"Two",@"Three",nil];
- for(NSString *string in array)
- {
- NSLog(@"string:%@",string);
- }
- NSDictionary
创建字典
- //- (id) initWithObjectsAndKeys;
- ctionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];
- NSString *string = [dictionary objectForKey:@"One"];
- NSLog(@"string:%@",string);
- NSLog(@"dictionary:%@",dictionary);
- [dictionary release];
练习题:将文本“成绩单.text”内容加载到内存中并按规定的格式输出出来
NSMutableDictionary
创建
- 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);
删除指定的字典
- [dictionary removeObjectForKey:@"3"];
- NSLog(@"dictionary:%@",dictionary);
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);
定义结构体并添加到NSArray里面
- typedef struct {
- float real;
- float imaginary;
- } ImaginaryNumber;
- ImaginaryNumber miNumber;
- miNumber.real = 1.1;
- miNumber.imaginary = 1.41;
- NSValue *miValue = [NSValue value:miNumber
- withObjCType:@encode(ImaginaryNumber)]; // encode using the type name
- ImaginaryNumber miNumber2;
- [miValue getValue:&miNumber2];
四、宏定义#define讲解
NSNumber
- + (NSNumber *)numberWithInt:(int)value;
- + (NSNumber *)numberWithDouble:(double)value;
- - (int)intValue;
- - (double)doubleValue;
NSNumber可以将基本数据类型包装起来,形成一个对象,这样就可以给其发送消息,装入NSArray中等等。
- NSNumber * intNumber=[NSNumber numberWithInt:100];
- NSNumber *floatNumber=[NSNUmber numberWithFloat:100.00];
- int i=[intNumber intValue];
- if([intNumber isEqualToNumber:floatNumber]) ....
NSNumber继承NSObject ,可以使用比较 compare: isEqual等消息
NSNull
IOS里面最小简单的类,里面只有一个方法+(NSNull*) null;
数学常用方法
数学常量:
- #define M_E 2.71828182845904523536028747135266250 // e
- #define M_LOG2E 1.44269504088896340735992468100189214 // log 2e
- #define M_LOG10E 0.434294481903251827651128918916605082 // log 10e
- #define M_LN2 0.693147180559945309417232121458176568 // log e2
- #define M_LN10 2.30258509299404568401799145468436421 // log e10
- #define M_PI 3.14159265358979323846264338327950288 // pi
- #define M_PI_2 1.57079632679489661923132169163975144 // pi/2
- #define M_PI_4 0.785398163397448309615660845819875721 // pi/4
- #define M_1_PI 0.318309886183790671537767526745028724 // 1/pi
- #define M_2_PI 0.636619772367581343075535053490057448 // 2/pi
- #define M_2_SQRTPI 1.12837916709551257389615890312154517 // 2/sqrt(pi)
- #define M_SQRT2 1.41421356237309504880168872420969808 // sqrt(2)
- #define M_SQRT1_2 0.707106781186547524400844362104849039 // 1/sqrt(2)
常用函数:
指数运算
- NSLog(@"%.f", pow(3,2) ); //result 9
- NSLog(@"%.f", pow(3,3) ); //result 27
开平方运算(计算两点间的距离时用到)
- NSLog(@"%.f", sqrt(16) ); //result 4
- NSLog(@"%.f", sqrt(81) ); //result 9
上舍入
- NSLog(@"res: %.f", ceil(3.000000000001)); //result 4
- NSLog(@"res: %.f", ceil(3.00)); //result 3
下舍入
- NSLog(@"res: %.f", floor(3.000000000001)); //result 3
- NSLog(@"res: %.f", floor(3.9999999)); //result 3
四舍五入
- NSLog(@"res: %.f", round(3.5)); //result 4
- NSLog(@"res: %.f", round(3.46)); //result 3
- NSLog(@"res: %.f", round(-3.5)); //NB: this one returns -4
最小值
- NSLog(@"res: %.f", fmin(5,10)); //result 5
最大值
- NSLog(@"res: %.f", fmax(5,10)); //result 10
绝对值
- NSLog(@"res: %.f", fabs(10)); //result 10
- NSLog(@"res: %.f", fabs(-10)); //result 10
NSDate
得到当前的日期
- NSDate *date = [NSDate date];
日期之间比较可用以下方法
- - (BOOL)isEqualToDate:(NSDate *)otherDate;// 与otherDate比较,相同返回YES
- - (NSDate *)earlierDate:(NSDate *)anotherDate;// 与anotherDate比较,返回较早的那个日期
- - (NSDate *)laterDate:(NSDate *)anotherDate;//与anotherDate比较,返回较晚的那个日期
将日期转换成字符串
- NSLog(@”date = %@”,[data description]);
设置日期显示格式
- NSDateFormatter *formatter =[[[NSDateFormatter alloc] init] autorelease];
- [formatter setTimeStyle:NSDateFormatterFullStyle]; //设置几种默认的显示效果
- [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss a"];//设置自定义的显示效果
- NSLog([formatter stringFromDate:date]);
NSData
- NSData-> NSString
- NSString *aString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
- NSString->NSData
- NSString *aString = @"1234abcd";
- NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];