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转自holydancer的CSDN专栏,原文地址:http://blog.csdn.net/holydancer/article/details/7343561
objective C中的字符串操作
在OC中创建字符串时,一般不使用C的方法,因为C将字符串作为字符数组,所以在操作时会有很多不方便的地方,在Cocoa中NSString集成的一些方法,可以很方便的操作字符串,下面举几个例子:
1、创建:
直接利用等号赋值
NSString * str1=@"我是字符串";
stringWithFormat方法
NSString *str2=[NSString stringWithFormat:@"我是参数字符串%d,%d",11,111"];
2,合并:
NSString 字符串是不可改变的,可以在原字符串的基础上生成新的字符串,但是原字符串并没有改变,但是NSString 提供了一个子类:NSMutableString.该类是可变的,NSString可用的方法也同样适用于NSMutableString,但是使用之前要预先声明:
NSMutableString *str3 = [NSMutableString stringWithCapacity:50];
需要注意的是,该处声明时虽然给了50的容量,但是NSMutableString会自动扩充,所以不用担心给的空间小了。
创建了NSMutableString字符串,我们就可以进行合并操作了,常用方法有:
以上代码输出结果为:“NSString字符串5”;
3,删减:
字符串的删减,需要用到一个辅助结构体:NSRange;
NSRange的两个属性length,location,既可用于图形辅助,又可用于字符串辅助,在字符串辅助中,表示字符串中的一段范围,location指起始位置,length指包含字符的个数。创建NSRange的方法有三种:
(一)
NSRange range;
range.location = 10;
range.length = 2;
(二)
NSRange range={10,2};
(三)
NSRange range=NSMakeRange(10,2);//此种方法较为常用。
下面看段代码,如何使用NSRange辅助修改字符串内容:
输出结果如下:
I holydancer,2,2
4,比较:
(一)是否相等的比较:
和java中某些情况类似,字符串并不能直接用==比较,==比较的是两个字符串是否是同一个对象,而我们要比较的通常是两个字符串是否相等,这时应该使用isEqualToString,而不是用==比较其指针值。isEqualToString的返回值是BOOL类型,为YES和NO。
(二)字符串大小的比较:
字符串根据排列顺序的不同,会有大小的差异,如果我们要比较两个字符串的大小的话,可以使用compare方法。compare 方法返回的结果有三种:NSOrderedAscending,NSOrderedSame,NSOrderedDescending,另外,在使用compare方法时可以添加参数来决定是否区分大小写,或者声明为比较字符串个数而不是字符值等比较条件。
具体使用看如下DEMO:
如果要忽略大小写的话,可以在options 里面加一个参数NSCaseInsensitiveSearch;具体如下
NSComparisonResult result2 =[str1 compare:str2 options:NSCaseInsensitiveSearch];
和NSCaseInsensitiveSearch对应的条件还有NSLiteralSearch(区分大小写),NSNumericSearch(按字符个数比较),并可以使用"|"来同时满足多个条件。
(三)判断字符串的开头和结尾
hasPrefix方法判断是否以某字符串开头,hasSuffix判断是否以某字符串结尾。
关键字:objective-c ,objective c , oc ,字符串
一、效果图:
二、布局文件
header_view.xml
<?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app1="http://schemas.android.com/apk/res/com.johnny.flowindicatortest" android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="vertical" > <Gallery android:id="@+id/home_gallery" android:layout_width="fill_parent" android:layout_height="wrap_content" android:spacing="5dp" /> <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="bottom" android:background="#65000000" android:orientation="vertical" > <TextView android:id="@+id/tv_gal_title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:layout_marginBottom="5dp" android:layout_marginTop="5dp" android:textColor="#ffffff" android:textSize="18sp" /> <com.johnny.flowindicatortest.FlowIndicator android:id="@+id/myview" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginBottom="5dip" android:gravity="center" app:count="4" app:point_normal_color="#45000000" app:point_radius="3dip" app:point_seleted_color="#ffffff" app:point_size="5dip" app:space="10dp" /> </LinearLayout> </FrameLayout>
gallery_item.xml
<?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <ImageView android:id="@+id/home_img" android:layout_width="wrap_content" android:layout_height="wrap_content" android:adjustViewBounds="true" android:src="/blog_article/@drawable/t1/index.html" /> </FrameLayout>
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="FlowIndicator"> <attr name="count" format="integer" /> <attr name="space" format="dimension" /> <attr name="point_size" format="dimension" /> <attr name="point_seleted_color" format="color|reference" /> <attr name="point_normal_color" format="color|reference" /> <attr name="point_radius" format="dimension" /> </declare-styleable> </resources>FlowIndicator.java
public class FlowIndicator extends View { private int count; private float space, radius; private int point_normal_color, point_seleted_color; // 选中 private int seleted = 0; public FlowIndicator(Context context, AttributeSet attrs) { super(context, attrs); // TODO Auto-generated constructor stub //提供TypedArray(用于Drawable对象数组)的XML资源。 TypedArray typedArray = context.obtainStyledAttributes(attrs,R.styleable.FlowIndicator); count = typedArray.getInteger(R.styleable.FlowIndicator_count,4); space = typedArray.getDimension(R.styleable.FlowIndicator_space, 9); radius = typedArray.getDimension(R.styleable.FlowIndicator_point_radius, 9); point_normal_color = typedArray.getColor(R.styleable.FlowIndicator_point_normal_color, 0x000000); point_seleted_color = typedArray.getColor(R.styleable.FlowIndicator_point_seleted_color, 0xffff07); int sum = attrs.getAttributeCount(); if(Constans.DEBUG){ String str = ""; for(int i=0;i<sum;i++){ String name = attrs.getAttributeName(i); String value = attrs.getAttributeValue(i); str += "sttr_name:" + name +": " + value +"\n"; } Log.i("attribute", str); } typedArray.recycle(); } public void setSeletion(int index){ this.seleted = index; //重绘 invalidate(); } public void setCount(int count){ this.count = count; invalidate(); } public void next(){ if(seleted < count-1){ seleted++; }else{ seleted = 0; } invalidate(); } public void previous(){ if(seleted > 0 ){ seleted--; }else{ seleted = count-1; } invalidate(); } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); Paint paint = new Paint(); paint.setAntiAlias(true); float width = (getWidth() - ((radius * 2 * count) + (space * (count - 1))))/2.f; for (int i = 0; i < count; i++) { if (i == seleted) paint.setColor(point_seleted_color); else paint.setColor(point_normal_color); canvas.drawCircle(width + getPaddingLeft() + radius + i * (space + radius + radius), getHeight() / 2, radius, paint); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec)); } private int measureWidth(int measureSpec) { int result = 0; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) { result = specSize; } else { result = (int) (getPaddingLeft() + getPaddingRight() + (count * 2 * radius) + (count - 1) * radius + 1); if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return result; } private int measureHeight(int measureSpec) { int result = 0; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) { result = specSize; } else { result = (int) (2 * radius + getPaddingTop() + getPaddingBottom() + 1); if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return result; } }MainActivity.java
public class MainActivity extends Activity { private static final int SCROLL_ACTION = 0; private TextView textView; private Gallery mGallery; private FlowIndicator myView; Timer mTimer; private GalleryAdapter galleryAdapter; private String[] titles = {"标题1","标题2","标题3","标题4","标题5","标题6","标题7","标题8","标题9"}; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.header_view); viewInit(); //定时滚动 mTimer = new Timer(); mTimer.scheduleAtFixedRate(new MyTask(), 0, 5000); } private void viewInit(){ textView = (TextView) findViewById(R.id.tv_gal_title); mGallery = (Gallery) findViewById(R.id.home_gallery); myView = (FlowIndicator) findViewById(R.id.myview); galleryAdapter = new GalleryAdapter(this); myView.setCount(galleryAdapter.getCount()); mGallery.setAdapter(galleryAdapter); mGallery.setOnItemSelectedListener(new OnItemSelectedListener() { @Override public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub textView.setText(titles[arg2]); myView.setSeletion(arg2); } @Override public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub } }); } private class GalleryAdapter extends BaseAdapter{ Context mContext; int[] res = new int[] { R.drawable.t1, R.drawable.t2, R.drawable.t3, R.drawable.t1, R.drawable.t2, R.drawable.t3, R.drawable.t1, R.drawable.t2, R.drawable.t3 }; public GalleryAdapter(Context cnt) { this.mContext = cnt; } @Override public int getCount() { // TODO Auto-generated method stub return res.length; } @Override public Object getItem(int arg0) { // TODO Auto-generated method stub return res[arg0]; } @Override public long getItemId(int arg0) { // TODO Auto-generated method stub return arg0; } @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub if(convertView == null){ convertView = LayoutInflater.from(mContext).inflate(R.layout.gallery_item, null); } ImageView imageView = (ImageView) convertView.findViewById(R.id.home_img); imageView.setImageResource(res[position]); return convertView; } } private class MyTask extends TimerTask { @Override public void run() { mHandler.sendEmptyMessage(SCROLL_ACTION); } } Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); switch (msg.what) { case SCROLL_ACTION: MotionEvent e1 = MotionEvent.obtain(SystemClock.uptimeMillis(), SystemClock.uptimeMillis(), MotionEvent.ACTION_DOWN, 89.333336f, 265.33334f, 0); MotionEvent e2 = MotionEvent.obtain(SystemClock.uptimeMillis(), SystemClock.uptimeMillis(), MotionEvent.ACTION_UP, 300.0f, 238.00003f, 0); mGallery.onFling(e1, e2, -1300, 0); break; default: break; } } }; }Constans.java
public class Constans { public static boolean DEBUG = true; }
<style> /* center icons */ .ui-grid-a { text-align: center; } /* set row height */ .ui-block-a, .ui-block-b { height: 150px; position: relative; } /* set label size and color */ .icon-label { color:#009966; display: block; font-size:12px; } /* position the icons at the bottom of the block to adjust for uneven icon heights */ .icon-springboard { position: absolute; bottom: 0; width: 100%;} a:link, a:visited, a:hover, a:active { text-decoration:none; } </style>
<div data-role="content" data-theme="b"> <div > <div > <div > <a href="#" > <img src="/blog_article/images/Live%20Mail.png" alt="Coming Soon" > <span >收件箱</span> </a> </div> </div> <div > <div > <a href="#"> <img src="/blog_article/images/Email%20Chat.png" alt="Coming Soon" > <span >已发邮件</span> </a> </div> </div> <div > <div > <a href="#" > <img src="/blog_article/images/myspace_grn.png" alt="Coming Soon" > <span >通讯录</span> </a> </div> </div> <div > <div > <a href="#"> <img src="/blog_article/images/Google%20Drive%20Folder.png" alt="Coming Soon" > <span >网络硬盘</span> </a> </div> </div> <div > <div > <a href="#"> <img src="/blog_article/images/Gmai%20lalt.png" alt="Tickets" > <span >写邮件</span> </a> </div> </div> <div > <div > <a href="/blog_article/ch4/contact-us.html"> <img src="/blog_article/images/Gmail.png" alt="Contact Us" > <span >我的邮件</span> </a> </div> </div> </div> </div>