iOS开发 字符串的转化 小技巧

/字典或者数组转化为nsstring

NSArray *arr = [NSArray arrayWithObject:@"1"];

NSString *str = [arr JSONString];               //数组或者字典转化为json串

NSArray *arr1 = [str objectFromJSONString];     //json串转化为字典或者数组

NSData *data = [arr1 JSONData];                 //把json串转化为nsdata

NSString *str1 = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];//把NSdata转为为NSString
    NSData *data1 = [str1 dataUsingEncoding:NSUTF8StringEncoding]; //把NSString转化为NSData

//二进制流转变为字符串

NSString *str=[[NSMutableString alloc] initWithData:self.receiveDataencoding:NSUTF8StringEncoding];

//转变其中的内容

str=[str stringByReplacingOccurrencesOfString:@"," withString:@",\n"];

str=[str stringByReplacingOccurrencesOfString:@"{" withString:@"{\n"];

str=[str stringByReplacingOccurrencesOfString:@"}" withString:@"\n}"];

NSLog(@"%@",str);

//把字符串再转变为二进制流

self.receiveData=[NSMutableData dataWithData:[str dataUsingEncoding:NSUTF8StringEncoding]];

//request转变为URL

NSURL *url=[request URL];

//URL转变为nsstring

NSString *str=[[url absoluteString] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSLog(@"%@",str);

NSURL *url=[NSURL URLWithString:@"http://img3.xooimage.com/files/6/1/3/firefox-logo-200x200-19f78a.png"];

//网站转变为二进制流

NSMutableData *data=[NSMutableData dataWithContentsOfURL:url];

UIImage *image=[UIImage imageWithData:data];

//读取文件

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Students" ofType:@"xml"];

//文件转变为二进制流

NSData *data = [NSData dataWithContentsOfFile:filePath];

//取出首字母

NSString *name = [city objectForKey:@"name"];

NSString *firstStr=[name substringWithRange:NSMakeRange(0, 1)];

//从一个字符串中直接取出数组

NSString *str = [NSString stringWithFormat:@"Norman,Stanley,Fletcher"];

NSArray *arr = [str componentsSeparatedByString:@","];

NSLog(@"arr = %@",arr);

//转码

urlStr = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];