Objective-C个人学习系列(1) NSString NSMutableString
// 字符初始化
void initStaticString(){
NSString *s1 = @"abc";//[NSString stringWithString:@"abc"];
NSString *ss1 = [[NSString alloc] initWithString:s1];
NSString *s2 = [NSString stringWithFormat:@"abcd"];
NSString *s3 = [NSString stringWithUTF8String:"abcde"];
NSString *s4 = [NSString stringWithCString:"abc123" encoding:NSUTF8StringEncoding];
NSString *s5 = [NSString stringWithContentsOfURL:
[NSURL URLWithString:@"www.baidu.com"]
encoding:NSUTF8StringEncoding error:nil];
}
// 字符串截取
void mysubString(){
NSString *str=@"abcdefg123456";
//计算字符串长度
unsigned long n = [str length];
NSLog(@"%ld",n);
//从第3个位置开始截取，索引从3开始
NSLog(@"%@",[str substringFromIndex:3]); //Output:defg123456
//截取到第3个位置,索引到3-1，不包括3
NSLog(@"%@",[str substringToIndex:3]); //Output:abc
//截取一段字符串，从2开始的5个字符串
NSRange range = NSMakeRange(2, 5); //声明结构体
NSLog(@"%@",[str substringWithRange:range]); //Output:cdefg
//
NSLog(@"%@",[str substringWithRange:NSMakeRange(2, 5)]); //Output:cdefg
NSString *str2=@"1,2,3,a,b,c";
//字符串分割
NSArray *array=[str2 componentsSeparatedByString:@","]; //Output:(1,2,3,a,b,c)
NSLog(@"%@",array);
NSRange rangeSub = [str rangeOfString:@"defg"];
//查找子串首字母在父串中的索引位置
NSLog(@"range.location=%ld",rangeSub.location); //Output:3
//查找子串在父串中占的长度，大于0表示找到了，等于0表示没找到
NSLog(@"range.length=%ld",rangeSub.length); //Output:4
}
//可变字符串 NSMutableString
void multalbeString(){
NSMutableString *mStr = [[NSMutableString alloc] initWithCapacity:0];
[mStr appendString:@"This is MutableString!"];
NSLog(@"%@",mStr); //Output:This is MutableString!
//在原字符串后面添加格式化字符串
[mStr appendFormat:@"My age is %d\n",23];
NSLog(@"%@",mStr); //Output:This is MutableString!My age is 23
//在原字符串指定位置开始插入字符串
[mStr insertString:@"AAA"atIndex: 8];
NSLog(@"%@",mStr); //Output:This is AAAMutableString!My age is 23
//删除指定范围内的一个子字符串
[mStr deleteCharactersInRange:NSMakeRange(0, 5)];
NSLog(@"%@",mStr); //Output:is AAAMutableString!My age is 23
//替换指定范围内的一个子字符串
[mStr replaceCharactersInRange:NSMakeRange(3, 3) withString:@"BBB"];
NSLog(@"%@",mStr); //Output:is BBBMutableString!My age is 23
}
void stringOther(){
NSMutableString *mStr = [[NSMutableString alloc] initWithCapacity:0];
[mStr appendString:@"abc abc abc WO WO WO!"];
//转换为大写，返回一个大写的新字符串
NSString* up = [mStr uppercaseString];
NSLog(@"up=%@",up);
NSLog(@"mstr=%@",mStr);
//转换为小写，返回一个小写的新字符串
NSString* low = [mStr lowercaseString];
NSLog(@"low=%@",low);
//返回一个首字母转换成大写的字符串
NSString* Abc = [mStr capitalizedString];
NSLog(@"Abc=%@",Abc);
}
//判断前缀后缀
void stringPreSuf(){
NSString* strURL = @"http://www.music.com/10/love.mp3";
BOOL isHasPrefix = [strURL hasPrefix:@"http://"];
BOOL hasSuffix = [strURL hasSuffix:@".mp3"];
NSLog(@"%d",isHasPrefix);
NSLog(@"%d",hasSuffix);
}
//字符串比较
void stringComare(){
NSString* s1 = @"abc";
NSString* ss1 = @"abc"; //此处ss1 s1 指向的是同一个地址
NSString* s2 = [[NSString alloc]initWithFormat:@"abc"];
if ([s1 isEqualToString:s2]) { //比较字符串的值
NSLog(@"OK!");
}
if (s1 == s2) { //比较字符串的地址，s1==s2 为假 s1==ss1 为真
NSLog(@"OK!");
}
int n = [s1 compare:s2]; //1,0,-1
NSLog(@"%d",n);
}