整理了一下在iOS开发中常见的问题及解决办法，希望会帮助到有需要的你。
1.去掉tableview header的黏性
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
[self.searchBar resignFirstResponder];
if (scrollView == self.listTableView) {
CGFloat sectionHeaderHeight = HEADVIEW_HIGHT;
if (scrollView.contentOffset.y<=sectionHeaderHeight&&scrollView.contentOffset.y>=0) {
scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);
} else if (scrollView.contentOffset.y>=sectionHeaderHeight) {
scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);
}
}
}
2.拖动tableView时收起键盘
只有一行代码:
tableView.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;
其中keyboardDismissMode是UIScrollView的属性,
它的值除了UIScrollViewKeyboardDismissModeNone,
还有一种是UIScrollViewKeyboardDismissModeInteractive,
表示键盘可以随着手指下滑而移出屏幕
既然是UIScrollView的属性,那么在文字常用的UITextView等控件中也可以使用.
3.获取某个view所在的控制器
- (UIViewController *)viewController
{
UIViewController *viewController = nil;
UIResponder *next = self.nextResponder;
while (next)
{
if ([next isKindOfClass:[UIViewController class]])
{
viewController = (UIViewController *)next;
break;
}
next = next.nextResponder;
}
return viewController;
}
4.获取图片某一点的颜色
- (UIColor*) getPixelColorAtLocation:(CGPoint)pointinImage:(UIImage *)image
{
UIColor* color = nil;
CGImageRef inImage = image.CGImage;
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
if (cgctx == NULL) {
return nil; /* error */
}
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRectrect = {{0,0},{w,h}};
CGContextDrawImage(cgctx, rect, inImage);
unsigned char* data = CGBitmapContextGetData (cgctx);
if (data != NULL) {
int offset = 4*((w*round(point.y))+round(point.x));
int alpha = data[offset];
int red = data[offset+1];
int green = data[offset+2];
int blue = data[offset+3];
color = [UIColorcolorWithRed:(red/255.0f) green:(green/255.0f) blue:
(blue/255.0f) alpha:(alpha/255.0f)];
}
CGContextRelease(cgctx);
if (data) {
free(data);
}
return color;
}
5.字符串反转
//第一种方法：
- (NSString *)reverseWordsInString:(NSString *)str
{
NSMutableString *newString = [[NSMutableStringalloc] initWithCapacity:str.length];
for (NSInteger i = str.length - 1; i >= 0 ; i --)
{
unicharch = [strcharacterAtIndex:i];
[newStringappendFormat:@"%c", ch];
}
return newString;
}
//第二种方法：
- (NSString*)reverseWordsInString:(NSString*)str
{
NSMutableString *reverString = [NSMutableStringstringWithCapacity:str.length];
[strenumerateSubstringsInRange:NSMakeRange(0, str.length) options:NSStringEnumerationReverse | NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString *substring, NSRangesubstringRange, NSRangeenclosingRange, BOOL *stop) {
[reverStringappendString:substring];
}];
return reverString;
}
7.禁止锁屏
默认情况下，当设备一段时间没有触控动作时，iOS会锁住屏幕。但有一些应用是不需要锁屏的，比如视频播放器。
[UIApplicationsharedApplication].idleTimerDisabled = YES;
或
[[UIApplicationsharedApplication] setIdleTimerDisabled:YES];
8.获取汉字的拼音
+ (NSString *)transform:(NSString *)chinese
{
//将NSString装换成NSMutableString
NSMutableString *pinyin = [chinese mutableCopy];
//将汉字转换为拼音(带音标)
CFStringTransform((__bridgeCFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);
NSLog(@"%@", pinyin);
//去掉拼音的音标
CFStringTransform((__bridgeCFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);
NSLog(@"%@", pinyin);
//返回最近结果
return pinyin;
}
9.手动更改iOS状态栏的颜色
- (void)setStatusBarBackgroundColor:(UIColor *)color
{
UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];
if ([statusBar respondsToSelector:@selector(setBackgroundColor:)])
{
statusBar.backgroundColor = color;
}
}
10.判断当前ViewController的跳转方式是push还是present
NSArray *viewcontrollers=self.navigationController.viewControllers;
if (viewcontrollers.count > 1)
{
if ([viewcontrollers objectAtIndex:viewcontrollers.count - 1] == self)
{
//push方式
[self.navigationController popViewControllerAnimated:YES];
}
}
else
{
//present方式
[self dismissViewControllerAnimated:YEScompletion:nil];
}
11.修改UITextField中Placeholder的文字颜色
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
12.根据色值生成图片
- (UIImage *)imageWithColor:(UIColor *)color
{
CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRefcontext = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [colorCGColor]);
CGContextFillRect(context, rect);
UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return theImage;
}
第一部分就先到这里，后续会继续总结，敬请期待。
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