Objective-C 記錄

NSdata 與 NSString，Byte數組，UIImage 的相互轉換

原文網址：http://www.cnblogs.com/jacktu/archive/2011/11/08/2241528.html

1. NSData 與 NSString
NSData－> NSString
NSString *aString = [[NSString alloc] initWithData:adata encoding:NSUTF8StringEncoding];

NSString－>NSData
NSString *aString = @"1234abcd";
NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

2.NSData 與 Byte
NSData－> Byte數組
NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];
for(int i=0;i<[testData length];i++)
printf("testByte = %d\n",testByte[i]);

Byte數組－> 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];

Byte數組－>16進制數
Byte *bytes = (Byte *)[aData bytes];
NSString *hexStr=@"";
for(int i=0;i<[encryData length];i++)
{
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff]; ///16進制數
if([newHexStr length]==1)
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
else
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
NSLog(@"bytes 的16進制數爲:%@",hexStr);

16進制數－>Byte數組
///// 將16進制數據轉化成Byte 數組
NSString *hexString = @"3e435fab9c34891f"; //16進制字符串
int j=0;
Byte bytes[128]; 

 ///3ds key的Byte 數組， 128位
for(int i=0;i<[hexString length];i++)
{
int int_ch;  /// 兩位16進制數轉化後的10進制數
 
unichar hex_char1 = [hexString characterAtIndex:i]; ////兩位16進制數中的第一位(高位*16)
int int_ch1;
if(hex_char1 >= '0' && hex_char1 <='9')
int_ch1 = (hex_char1-48)*16;   //// 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch1 = (hex_char1-55)*16; //// A 的Ascll - 65
else
int_ch1 = (hex_char1-87)*16; //// a 的Ascll - 97
i++;
 
unichar hex_char2 = [hexString characterAtIndex:i]; ///兩位16進制數中的第二位(低位)
int int_ch2;
if(hex_char2 >= '0' && hex_char2 <='9')
int_ch2 = (hex_char2-48); //// 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch2 = hex_char2-55; //// A 的Ascll - 65
else
int_ch2 = hex_char2-87; //// a 的Ascll - 97
 
int_ch = int_ch1+int_ch2;
NSLog(@"int_ch=%d",int_ch);
bytes[j] = int_ch;  ///將轉化後的數放入Byte數組裏
j++;
}
NSData *newData = [[NSData alloc] initWithBytes:bytes length:128];
NSLog(@"newData=%@",newData);

3. NSData 與 UIImage
NSData－>UIImage
UIImage *aimage = [UIImage imageWithData: imageData];
 
//例：從本地文件沙盒中取圖片並轉換爲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);

 

原文網址：http://blog.sina.com.cn/s/blog_6268f10201015ak8.html

以binary來收藏容納文件

NSData生成:

NSDictionary *dic =[NSDictionary dictionaryWithObject:@"hello" forKey:@"KEY"];

NSData *d = [NSKeyedArchiver archivedDataWithRootObject:dic];

 

從文件生成NSData:

NSBundle *bundle = [NSBundle mainBundle];

NSString *path = [bundle pathForResource:@"hello"  ofType:@"png"];

NSData *d = [[NSData alloc] initWithContentsOfFile:  path];

 

取得元素長度:

int i = [d length];

 

NSData型轉成NSDictionary型:

NSDictionary *reverse = [NSKeyedUnarchiver unarchiveObjectWithData: d];

NSData *data = [NSData dataWithContentsOfFile:filePath];
NSUInteger len = [data length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [data bytes], len);

NSString *strPath = @"/Users/user/Desktop/jkk.txt";
NSLog(@"string = %@",[[NSString alloc]initWithContentsOfFile:strPath encoding:NSUTF8StringEncoding error:Nil]);
NSData *strData = [[NSData alloc]initWithContentsOfFile:strPath];
NSLog(@"size = %d字節; strData = %@",strData.length,strData.description);

NSUInteger len = [strData length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [strData bytes], len);

for (int i = 0; i < len; i++) {
printf("%c",byteData[i]);
}


NSData *Data222 = [[NSData alloc]initWithBytes:byteData length:len];
NSLog(@"Data222 : %@",Data222);

NSRange rangeData = {0,3};
NSData *subData = [strData subdataWithRange:rangeData];
NSLog(@"subData : %@",subData);

NSData *Data333 = [[NSData alloc]initWithData:subData];
NSLog(@"Data333: %@",[[NSString alloc]initWithData:Data333 encoding:NSUTF8StringEncoding]);

How to turn 4 bytes into a float in objective-c from NSData

原文網址：http://stackoverflow.com/questions/30608669/how-to-turn-4-bytes-into-a-float-in-objective-c-from-nsdata

NSData* data = [NSData dataWithContentsOfFile:@"/tmp/java/test.dat"]; int32_t bytes; [data getBytes:&bytes length:sizeof(bytes)]; bytes = OSSwapBigToHostInt32(bytes); float number; memcpy(&number, &bytes, sizeof(bytes)); NSLog(@"Float %f", number);



NSString與int和float的相互轉換

NSString *tempA = @"123";

NSString *tempB = @"456";

1，字符串拼接

 NSString *newString = [NSString stringWithFormat:@"%@%@",tempA,tempB];

2，字符轉int

int intString = [newString intValue];

3，int轉字符

NSString *stringInt = [NSString stringWithFormat:@"%d",intString];

4，字符轉float

 float floatString = [newString floatValue]

5，float轉字符

NSString *stringFloat = [NSString stringWithFormat:@"%f",intString];

iPhone: @selector 裏面的方法名加參數 NSTimer and that thing called userInfo  

NSTimer攜帶傳遞值
NSTimer有個屬性 叫userInfo，下面的方法的第四個參數userInfo

+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;

 userinfo用NSTimer的實例能夠得到，返回類型是 id
 [timer userInfo];

 

[NSTimer scheduledTimerWithTimeInterval:0.25 target:self selector:@selector(handleTimer:) userInfo:@"參數" repeats:YES];
用的時候只要在下面函數裏調用強制轉換的userinfo就行，
-(void)handleTimer:(NSTimer*)timer
{
//這裏使用(NSString *)[timer userInfo]
}

-(void)handleTimer:(NSTimer*)timer

這裏最好用id作參數
-(void)handleTimer:(id)timer

 

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];  

    if(oldView != nil){

        [dict setObject:oldView forKey:@"oldView"]; 

    }

    if(newView != nil){

        [dict setObject:newView forKey:@"newView"]; 

    } 

    [NSTimer scheduledTimerWithTimeInterval:0.0 target:self selector:@selector(onTimer:) userInfo:dict repeats:NO];  

    [dict release];

 

 

- (void)onTimer:(NSTimer *)timer {  

    UIView *oldView = [[timer userInfo] objectForKey:@"oldView"];

    UIView *newView = [[timer userInfo] objectForKey:@"newView"];  

    [UIView animateWithDuration:2.0  delay:0

                        options:UIViewAnimationOptionAllowUserInteraction

                     animations:^{  

                         oldView.alpha = 0.0; 

                         newView.alpha = 1.0;  

                     }  

4.在學習OC代碼的時候，編譯oc .m文件有以下兩種方式(1) clang -fobjc-arc -framework Foundation Hello.m -o hello.out

./hello.out

(2) 用xcode編譯.m後生成的可執行文件hello和源碼hello.m不在同一個目錄

經過右擊 hello, show in finder能夠找到hello可執行文件

或者經過下面的代碼查看
To get the path to your file use

NSString * myFile = [[NSBundle mainBundle]pathForResource:@"Alert" ofType:@"txt"];
NSFileManager *fileManager = [NSFileManager defaultManager];
if ([fileManager fileExistsAtPath: myFile ]){
NSLog(@"good");
}
這個問題是在學習NSFileManger的時候，使用NSFileManger建立的文件，在源碼的文件夾中找不到，
上面的方式能夠查看到實際的路徑：
/Users/yqf/Library/Developer/Xcode/DerivedData/NSFileManagerTest2-eaeuwbogilljalgvxymvlvdqwjwb/Build/Products/Debug/NSFile

 5. Xcode workSpace與Project配置

原文網址：http://blog.sina.com.cn/s/blog_13edf9b370102w8r4.html

方式一 右鍵add

WorkSpace中添加已有的工程-方式1.png

• 注意點1 選擇工程時，選後綴名爲.xcodeproj 的工程配置文件，而不是選擇整個工程的父文件夾。

方式二 直接拖

• 注意點1 拖到面板的時候，鼠標要放在最上方，否則會致使工程

  
  

  WorkSpace中添加已有的工程-方式二-1.png

• 注意點2 只能託後綴名爲.xcodeproj 的工程配置文件

  
  

  WorkSpace中添加已有的工程-方式二-2.png

方式三

1. 直接選擇菜單欄中的new->project
   可是必須選擇ADD TO WorkSpace
   
   
   

   WorkSpace中添加已有的工程-方式三.png

6. 用NSScanner判斷String內容是否爲整型或者浮點型數據

原文網址：http://cocoa-chen.github.io/blog/2014/10/27/yong-nsscannerpan-duan-stringnei-rong-shi-fou-wei-zheng-xing-huo-zhe-fu-dian-xing-shu-ju/

在開發的過程當中會遇到各類各樣的需求,好比須要判斷一個NSString的變量內容是否爲Int數據或者Float數據,這時候能夠用NSScanner來簡單的判斷下

1.判斷NSString是否爲int內容

1 2 3 4 5 6 7 8

- (BOOL)isPureInt:(NSString *)string{ if (!string) { return NO; } NSScanner *_scanner = [NSScanner scannerWithString:string]; int val; return [_scanner scanInt:&val] && [_scanner isAtEnd]; }

調用測試以下：

1 2 3 4 5 6

NSString *pureIntString = @"123"; NSString *noPureIntString = @"123ab"; BOOL isPure1 = [self isPureInt:pureIntString]; NSLog(@"'%@'字符串%@int內容的字符串",pureIntString,isPure1 ? @"是" : @"不是"); BOOL isPure2 = [self isPureInt:noPureIntString]; NSLog(@"'%@'字符串%@int內容的字符串",noPureIntString,isPure2 ? @"是" : @"不是");

2.判斷NSString是否爲float內容

1 2 3 4 5 6 7 8

- (BOOL)isPureFloat:(NSString *)string{ if (!string) { return NO; } NSScanner* scan = [NSScanner scannerWithString:string]; float val; return [scan scanFloat:&val] && [scan isAtEnd]; }

調用測試以下：

1 2 3 4 5 6

NSString *pureFloatString = @"1.23"; NSString *nopureFloatString = @"1.23a"; BOOL isPure1 = [self isPureFloat:pureFloatString]; NSLog(@"'%@'字符串%@float內容的字符串",pureFloatString,isPure1 ? @"是" : @"不是"); BOOL isPure2 = [self isPureFloat:nopureFloatString]; NSLog(@"'%@'字符串%@float內容的字符串",nopureFloatString,isPure2 ? @"是" : @"不是");

NSScanner還提供其餘的API來檢測對應的數據類型，遇到對應的需求你們能夠嘗試使用一下！

7.  Objective-C 拆分字符串成數組（相似java 的 split）

原文網址：http://blog.csdn.net/sirodeng/article/details/8306288

在不少語言如 java , ruby , python中都有將字符串切分紅數組或者將數組元素以某個間隔字符串間隔造成新的數組。 其實NSArray也提供了這樣的功能。 

使用-componentsSeparatedByString:來切分NSArray。 如： 

引用

NSString *string = @」one:two:three」; 
NSArray *aArray = [string componentsSeparatedByString:@":"];

用-componentsJoinedByString:來合併NSArray中的各個元素並建立一個新的字符串，如： 
string = [aArray componentsJoinedByString:@","]; 

這樣，上面的數組就中的各個元素就以」,」分割造成一個字符串。

 8. ios 開發 NSArray 排序 （根據NSString的值排序）

原文網址：http://blog.csdn.net/wenluma/article/details/8705272

NSMutableArray *array =  [[NSMutableArray alloc] initWithObjects:@"1",@"3",@"5",@"40" nil];</span></p>NSArray *sorteArray = [array sortedArrayUsingComparator:^(id obj1, id obj2){
    if ([obj1 integerValue] > [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedDescending;
    }

    if ([obj1 integerValue] < [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedAscending;
    }

    return (NSComparisonResult)NSOrderedSame;
}];

NSLog(@"%@",sorteArray);            //從小到大


NSArray *array2 = [array sortedArrayUsingComparator:^(id obj1, id obj2){
    if ([obj1 integerValue] > [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedAscending;
    }

    if ([obj1 integerValue] < [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedDescending;
    }

    return (NSComparisonResult)NSOrderedSame;
}];

NSLog(@"%@",array2);

以上包含了有從小到大的排序，也包含有大到小的排序

若是是針對字符串的排序，有更好的方法，

 [cpp] view plain copy

NSArray *ary = @[@"a3",@"a1",@"a2",@"a10",@"a24"];
NSLog(@"%@",ary);
NSArray *myary = [ary sortedArrayUsingComparator:^(NSString * obj1, NSString * obj2){
    return (NSComparisonResult)[obj1 compare:obj2 options:NSNumericSearch];
}];
NSLog(@"%@",myary);
結果
 ( a3,a1, a2, a10, a24 )
 ( a1, a2,a3, a10, a24 )

NSArray *ary = @[@"a3",@"a1",@"a2",@"a24",@"a14"];
NSLog(@"%@",ary);
NSSortDescriptor *sd1 = [NSSortDescriptor sortDescriptorWithKey:nil ascending:NO];//yes升序排列，no,降序排列
NSArray *myary = [ary sortedArrayUsingDescriptors:[NSArray arrayWithObjects:sd1, nil]];//注意這裏的ary進行排序後會生產一個新的數組指針，myary，不能在用ary,ary仍是保持不變的。
NSLog(@"%@",myary);
//    (a3, a1, a2,a24,a14)
//    (a3, a24, a2, a14, a1)

[ary sortedArrayUsingSelector:@selector(compare:)];//這個是一直默認升序

 8. 判斷NSString是否包含某個字符串

在iOS8之後，還能夠用下面的方法來判斷是否包含某字符串：

//在iOS8中你能夠這樣判斷
    NSString *str = @"hello world"; if ([str containsString:@"world"]) { NSLog(@"str 包含 world"); } else { NSLog(@"str 不存在 world"); }

 29. objective-c 下面int 和 NSData數據 互相轉換的方法

原文網址：http://blog.csdn.net/ixfly/article/details/7662096

int i = 1; NSData *data = [NSData dataWithBytes: &i length: sizeof(i)];

int i; [data getBytes: &i length: sizeof(i)];