oc一些常见问题解决

1.__NSCFString containsString:]: unrecognized selector sent to instance 的解决方案

1 在IOS7上存在 IOS8上没有 

第一个解决方法是，把NSCFString转换为 NSString，使用最粗暴的方法[[request URL] absoluteString]

//第二种方法找NSString是不是有判断存在字符串的方法进入 NSCFStrng看是否有containsString这个方法

//第三种方法 将containsString替换成rangeOfString

2 NSMutableRLEArray objectAtIndex:effectiveRange:解决方法 

1 You can't convert an NSString to an NSMutableString simply by casting. Do this instead:

NSMutableString *string = [self.label.text mutableCopy]; http://stackoverflow.com/questions/19287154/nsmutablerlearray-objectatindexeffectiverange-out-of-bounds

2 第二种

NSMakeRange(i, j) creates a range with location i and length j.

If for example the size of your string is 10 and your range starts in 5, and you do this:

NSMakeRange(5,10)

Your range goes from 5 to 15, so out of your string.

Try:

NSMakeRange(newClock.length-3,3)]; // http://stackoverflow.com/questions/19344671/nsmutablerlearray-objectatindexeffectiverange-out-of-bounds

3 This coder requires that replaced objects be returned from initWithCoder:

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