常用类型转换

//NSString-->int 
int intString = [newString intValue];  
//int转字符 
NSString *stringInt = [NSString stringWithFormat:@"%d",intString];  

//NSString-->float 
float floatString = [newString floatValue];  
//float转NSString
NSString *stringFloat = [NSString stringWithFormat:@"%f",intString];  

//NSData-->NSString
NSString *aString = [[NSString alloc] initWithData:adata encoding:NSUTF8StringEncoding];
//NSString --> NSData
NSString *aString = @"1234";
NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

//NSData --> Byte
NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];
//Byte --> NSData
Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};
NSData *adata = [[NSData alloc] initWithBytes:byte length:24];

//NSData --> UIImage
UIImage *aimage = [UIImage imageWithData: imageData];
//例：从本地文件沙盒中取图片并转换为NSData
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *name = [NSString stringWithFormat:@"ceshi.png"];
NSString *finalPath = [path stringByAppendingPathComponent:name];
NSData *imageData = [NSData dataWithContentsOfFile: finalPath];
UIImage *aimage = [UIImage imageWithData: imageData];
//UIImage－> NSData
NSData *imageData = UIImagePNGRepresentation(aimae);


//NSData --> MSMutableData
NSData *data=[[NSData alloc]init];
NSMutableData *mdata=[[NSMutableData alloc]init];   
mdata=[NSData dataWithData:data];