iOS实用方法集锦（二）

UINavigationController Push过去的title不居中

NSArray *viewControllerArray = [self.navigationController viewControllers];

long previousViewControllerIndex = [viewControllerArray indexOfObject:self] - 1;
UIViewController *previous;

if (previousViewControllerIndex >= 0) {
previous = [viewControllerArray objectAtIndex:previousViewControllerIndex];
previous.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc]
initWithTitle:@""
style:UIBarButtonItemStylePlain
target:self
action:nil];
}

金额计算使用Fload和double精度不精确

- (NSString *)decimalNumberCalucate:(NSString *)originValue1 originValue2:(NSString *)originValue2 calucateWay:(NSInteger)calucateWay
{
NSDecimalNumberHandler *numUp = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundDown scale:2 raiseOnExactness:NO raiseOnOverflow:NO raiseOnUnderflow:NO raiseOnDivideByZero:YES];
NSDecimalNumber *decimalNumber1 = [NSDecimalNumber decimalNumberWithString:originValue1];
NSDecimalNumber *decimalNumber2 = [NSDecimalNumber decimalNumberWithString:originValue2];
NSDecimalNumber *product;
switch (calucateWay) {
case 1:
product = [decimalNumber1 decimalNumberByAdding:decimalNumber2 withBehavior:numUp];
break;

case 2:
product = [decimalNumber1 decimalNumberBySubtracting:decimalNumber2 withBehavior:numUp];
break;

case 3:
product = [decimalNumber1 decimalNumberByMultiplyingBy:decimalNumber2 withBehavior:numUp];
break;

case 4:
product = [decimalNumber1 decimalNumberByDividingBy:decimalNumber2 withBehavior:numUp];
break;

default:
break;
}

return [product stringValue];
}

数字千分位并保留两位小数

+ (NSString *)stringChangeDecimalStyleWith:(NSString *)string{
NSNumberFormatter *numformatter = [[NSNumberFormatter alloc] init];
[numformatter setPositiveFormat:@"###,##0.00;"];
NSString *str1 = [NSString stringWithFormat:@"%.2f",[string doubleValue]];
NSString *str2 = [numformatter stringFromNumber:[NSNumber numberWithDouble:[str1 doubleValue]]];
return str2;
}

获取label中某一段文字的frame（换行的暂未解决）

NSRange firRange = [xieyiStr rangeOfString:@"要获取的字符串" options:NSCaseInsensitiveSearch];
NSString *newstr = [@"一个完成的字符串中要获取的字符串所占据区域的frame" substringToIndex:secRange.location];
CGSize size = [prefix sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:14]}];
NSLog(@"%f",size.width);
CGRect newRect = CGRectMake(allLabel.frame.origin.x +size.width, allLabel.frame.origin.y, size.width, allLabel.frame.size.height);

判断点击的点是否在某一个区域（或者在某一个view中）

CGPathRef path = CGPathCreateWithRect(CGRectMake(0, 0, 100, 100), NULL);
point的获取方法，可以冲手势获取，也可以重touch获取
point的获取方法：
（1）手势获取
CGPoint point = [Recognizer locationInView:Recognizer.view];
（2）touch获取
UITouch *touch = touches.anyObject;
CGPoint point = [touch locationInView:touch.view];
（1）是否在某个区域
BOOL isInPath = CGPathContainsPoint(path, NULL, point, NO);
（2）是否在某个视图
BOOL isInView = CGRectContainsPoint(view.frame, point);

获取键盘的便宜高度

- (void)viewWillAppear:(BOOL)animated{
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
}
- (void)keyboardWillShow:(NSNotification *)notification{
NSDictionary *info = notification.userInfo;
NSValue *value = [info objectForKey:UIKeyboardFrameBeginUserInfoKey];
CGSize keyboardSize = [value CGRectValue].size;
CGFloat height  = keyboardSize.height;
}

切换摄像头

@property (nonatomic ,strong) AVCaptureSession *session;
NSUInteger cameraCount = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
if (cameraCount > 1) {
NSError *error;
AVCaptureDeviceInput *newVideoInput;
AVCaptureDevicePosition position = [[_inPut device] position];

if (position == AVCaptureDevicePositionBack)
newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontCamera] error:&error];
else if (position == AVCaptureDevicePositionFront)
newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self backCamera] error:&error];
else
return;

if (newVideoInput != nil) {
[self.session beginConfiguration];
[self.session removeInput:self.inPut];
if ([self.session canAddInput:newVideoInput]) {
[self.session addInput:newVideoInput];
//                [self setVideoInput:newVideoInput];
} else {
[self.session addInput:newVideoInput];
}
[self.session commitConfiguration];
} else if (error) {
NSLog(@"toggle carema failed, error = %@", error);
}
}

runtime拦截方法并替换方法

+ (BOOL)resolveInstanceMethod:(SEL)sel{
if (sel == @selector(dosomething)) {
NSLog(@"do");
class_addMethod([self class], sel, (IMP)changeMethodIMP, "v@:");
class_addMethod([self class], sel, (IMP)newMethod,"i@:@");
return YES;
}else{
return [super resolveInstanceMethod:sel];
}

}
void changeMethodIMP (id self , SEL _cmd){
NSLog(@"lod");
}
int newMethod (id self,SEL _cmd ,int str){
return 100;
}

OC简单调用JS

- (void)webViewDidFinishLoad:(UIWebView *)webView{
JSContext *cont = [webView valueForKeyPath:@"documentView.webView.mainFrame.javaScriptContext"];
//具体调用在下面的str中定义
NSString *str = @"alert ('test alert')";//一个类似uialertcontroller的弹窗
[cont evaluateScript:str];
}

未完待续，回继续收集并实践